I've tried, it sucks. Each broker has their own process, often several steps, and often a step is broken (like server errors, can't get past a captcha, "try again later", etc). You end up not just having to do the process, but also follow up with many of the ones that are ambiguous or returned server errors or whatnot. I did the top 8 or so brokers and then stopped.

Quite. Some of them make it as difficult as possible, requiring the request to be physically printed and sent in via the post. Some hide the information regarding how to make the request as obscurely as possible. And essentially none of them treat it as a 'and don't collect any more' request so they just start up a new collection on you the next time you do basically anything with one of their 'business partners.' Allowing people to request deletion is just the excuse they use to keep collection legal when it shouldn't be.

I used to spend one day each year doing all the opt outs and data delete requests i could find. it was going well for me until this year. i averaged about 2-3 spam emails a day, combined across 5 different emails, one was made all the way back in 1997 and two of them were made when gmail first started.

someone got breached this year, i don't know who, and now i get a lot more.

i also used firefox monitor to check for info on breach websites and darkweb lists, around the same time i started getting more spam, my list of breached info went from ~16 to 600+.