I would say not prepping enough for technical interviews. I did a lot of prep (hundreds of hours) but it wasn’t enough. I needed more because I was always being compared to senior engineers with 10+ years of XP who had been through the gauntlet a lot. Very few companies were ever explicating hiring for a junior or “mid” level role when I was looking. (Less than 3 years xp)

In the end, I realized I need to be doing interview prep pretty much all the time. Maybe give it up just before you start the next job and while you’re ramping up but it should just be routine once you hit 6 months or a year. There’s no reason to not do it because in all likelihood, you’ll be switching jobs.

I’m going into my sixth job in about 8 years now. I shouldn’t expect to stay at my next place longer than 2 years and thus should be prepping well before my planned time of exit.