Typically most full time jobs say nothing about time commitments. In the old days, pre-remote work, presence was often valued more than productivity at many companies. Today, “presence” is about keeping your slack dot green. Could you pull off over-employment with a small startup? Probably not. But a couple of bloated corporations? Absolutely.
I've only worked at 2 different mid-sized US tech companies but they both had "we expect you to work full-time, full-time is defined as 38-40 hours of work". Even if they didn't explicitly have that, if you're working a full-time job then that means you're working at least 30 hours otherwise it's not a full-time job by definition alone.
I typically avoid anything other than small companies. But with the last mid-size company I worked for, there definitely was not enough “real work” to fill 40 hours, or even 30. I had to learn to pace myself. But I still had to be available, on-site, during that time. With remote work “over employment”, people are taking advantage of those inefficiencies.
