I've walked out of interviews because of HR folks strongly implying that my side projects are for learning skills the company needs.
Could you explain what you mean here a little more? Did a company, at the interview phase, tell you they wanted you to work on side projects for free?
What they told me is that it's a good thing that I am familiar with so many technologies, since that probably indicates that I spend a lot of my own time perfecting my skills. Which is actually true. But then they began to rant about how that's a good thing because this is a competitive field and it's really hard to keep up with all the new technologies popping up, so I might have to put up some of my own time to learn the technologies we'll use.
I actually raised an eyebrow and said that no, I'm not willing to do that. This opened up a discussion about dedication and loving one's job beyond the matters of workhours and payment, which are true signs of a professional programmer, at which point I really just told them I'm not interested in their offer anymore and left.
At that point, I'd have left even if they'd have sworn I wouldn't have to do that and that they were just checking. It's really impolite. I don't presumptuously boast about how I know what really makes the difference between a professional medic and one who just has a license to practice. It's also manipulative in a really poor way, implying that if you don't do all that stuff, you're "just" a programmer, rather than a "professional" programmer. Yeah, no shit I'm a "professional programmer" -- I don't have kids, I live close to work, my girlfriend works from home so her schedule is more flexible than mine, everyone in my family is in good health and back in college I fucked up my sleep schedule so hard that the occasional all-nighter doesn't do much damage anymore. But I'm exactly as professional as the dude who comes in at 9 and leaves at 5 because his kids want their father, not his toys.
Companies use barely-functional pattern matching algorithms to automatically toss your resume into the garbage. It is very likely that any effort you spend hand-tailoring your self-advertisement will be wasted anyway. But let's assume that you're doing it to pass the bozo filter and talk to a real person.
If you have to feign specialization to get past the auto-rejector, it is safe to assume that the company sees fewer qualified candidates. Supply is lower. As long as the posting remains open, demand remains the same. Therefore, the more specialized the role, the higher your expected remuneration should be. It's fine that companies are picky, but not both picky and cheap.
My advice is to use a general, unmodified resume for all your initial applications, and only to tailor your resume if the company does not respond in person after the first 2 weeks. If that generates a response, remember to ask for a higher salary if you reach the negotiation phase.
Of course this, like most other advice, should be taken with skepticism, because it is based on my experiences, not yours.
Honestly, I don't spend much time customizing a resume, because I already have a job, even if I don't like it, and a lot of the postings that I see are just as flavorless and uninspired as an untailored resume. My primary criteria for applying are whether the job itself seems like it could be interesting after you subtract the HR boilerplate and whether the company makes it easy for people to submit themselves for consideration.
If applying is as easy as writing an e-mail with a resume attachment, I will take the time to write an original cover letter. If I have to jump through 8 pages of hoops where I have to re-enter my entire resume into a series of tiny text boxes, I will not customize anything. And on the 8th page, where I am asked to list 3 of my weaknesses in an HTML form, just above a request for my entire salary history, I will almost invariably list "I get snarky when confronted by foolish or wasteful hiring practices." At that point, I have already invested that much time on an application that I know will not yield fruit, so I can't help but feel bitter about the utter waste of it.
IMO this is stupid, self-destructive for companies and likely the result of cargo cult management.
My "generalist" palette is exactly what got me hired at each one of my previous jobs. I learned programming as a hobby long before going to university, and I got a degree in Instrumentation Engineering with what essentially amounts to a minor in Power Electronics. During the last two of my undergrad years I worked in a research team at my university and did a fairly good job (papers and all) in a third field, computational electromagnetism, mainly with applications in microelectronics.
This means, on one hand, that I can be very helpful to anyone in my team. I can help those of my colleagues who lean more towards software than hardware troubleshoot their instruments and development boards, and I can serve as a buffer between the hardware designers and the programmers. I can make good trade-offs between circuit-level design and high-level programming abstractions and I can design applications for low-power operation instead of writing something and tweaking it until it has decent battery life.
What this also means, though, is that people in management are ecstatic about how they can give me pretty much anything to work on, and I'll munch it, or stick me in the same room with people who think JS is the best thing and people who think computers are evil and still understand what each of them says. This enthusiasm comes from precisely the same people who whine about candidates who are "miles wide, inches deep", and I know of at least one instance when the lead developer who interviewed me had to kick and scream to get me hired because my CV painted me "undecided" and "not having a good career discipline". It's even more ironic considering that the people who whine about it are typically millimeters wide and deep.
I often hear this kind of discussion in the middle management circles. Our people are way too specialized and it makes communication and collaboration difficult; we could use people with a more diverse range of skills; we depend too much on one or two people doing this thing, but they're the only ones in the team who can do it. This is especially problematic in teams of people who have been in the company since they were juniors. Well no shit it is, since they just spent four out of the six years of their careers doing precisely the same thing.
And no, "side projects" are not a good solution to this, and I've walked out of interviews because of HR folks strongly implying that my side projects are for learning skills the company needs. Fuck off. Thinking and learning aren't free. You want it, you pay me.