This seems to be a good road to go down, but low hanging fruit skews this a bit. For example at my first IT job they used a system that text messaged customers to remind them of appointments. It cost $250 a month per office (12 offices), I took initiative (I was the only IT person in the company, I had very little management) and replaced it with an alternative I wrote in Python that used Twillo and brought that cost to below $5 a month per office. The savings were slightly greater than my salary (I also provided general IT services that were then basically free for them), but I wouldn't call myself a senior developer or a developer at all really as I've only held IT services jobs.