Use your data export to ensure you delete all your posts and comments before deleting your account. Using something like power delete suite does not get everything if you have a lot of activity on your account.
I ran into a “too many requests” a couple of times so I just put a 3 second cooldown on each request (it was naturally going like 1/second naturally through PRAW) took about 14 hours with my delay, but at least I didnt have to babysit it.
It seems like Reddit slowly starts filling in those deleted comments. In my experience, like as much as 5 per day. There’s no guarantee it’ll eventually get all comments even if ran repeatedly, and if you have 17k comments like me, it’s still probably take years to get all comments at that rate.