What if 'enough' is not time-based? What if you just have to make sure that new versions are deployed and the service stays up and isn't being hacked? If you can do that with 2 days/week, more power to you. Or maybe you put 6 days/week in at the outset, as an investment so that in a few months you'll be able to work a lot less?

> Or maybe you put 6 days/week in at the outset, as an investment so that in a few months you'll be able to work a lot less?

There are two outcomes in that situation.

1. Great, so you've gotten Service Foo stable! It now needs minimal dev attention. Since there's no shortage of work that needs to be done, and you've got 3 days/week free, it sounds like you're free to work on Service Bar, in addition to Service Foo.

2. Great, so you've gotten Service Foo stable. Now that it needs half the development attention that it used to, we no longer need a full-time person on it. Since we don't have any more work, we're laying you off (Or, in a fairy tale, where, for whatever reason, your manager values your contributions for what they were, laying one of your co-workers off.)

Personally, I prefer outcome #1. I'm paid to be at work, and do things, and if I get my work done faster then estimated, I'll get more work. And that's fine. The alternative is much worse.

I think there's a happy medium. I have a personal target of 4 days/week (or equivalent), and so I don't mind optimizing existing work, and then taking on additional work, as long as it averages out to this healthy balance. I have found that the best motivator for me is a manager who is able to say "you've done great work, you can relax for a bit, take some time off". I'll work hard for them, knowing they have my back and I don't have to fight and scrape for well-deserved rest. If they won't say that, and will just let me work as much as I can, then I start making clear boundaries around my work; and overall I am less motivated to make things better.