LeechBlock NG (the browser extension) has a "delay" mode of blocking. Make sure you enable "count only active tab" or it will waste much RAM and CPU.

With full blocking I used to cheat by disabling the block, and then "forgot" to enable it again.

With delay-based blocking I'm also cheating: instead of waiting for the delay I get up and do some minor chore. I used to feel smug about how clever I was, sabotaging my own block. Until I realized what a positive change this was.

PS: I've waited 40s to submit this comment. You'll need another plugin to recover the text if you submit and then hit the delay page. Or submit before the timer runs out.