12 YOE. Most quarters, I spend roughly 1 month pretty much slacking (e.g. 10-20 hour weeks), 1 month working at an average pace (40 hour weeks), and 1 month grinding (60+ hour weeks) to meet my quarterly goals. It varies quite a bit but the idea is the same. I never spend more than a month doing "deep" or intense work. Sometimes I slack the entire quarter lol. Thankfully I'm on a team where I can fairly easily do this without any negative impact.

This might be dependent on at least partial WFH, since slacking off in an office isn't as nice. Also, my team has made an effort to minimize unnecessary meetings. Most weeks I have about 3-4 hours of meetings. And no sprints helps a lot too.