What to expect after filing past due returns

I mailed returns for 2019 - 2025 (current due return plus 6 prior years - the last year that I filed was 2016, but my understanding is that the prior six is enough to be considered current) on 4/14, and certified mail tracking shows they were received on 4/17. No real reason or story why they hadn’t been filed on time, I just didn’t file on time one year and then every year after that it became a bigger and bigger stressor that I chose to avoid rather than dealing with. This year I finally decided to get it done.

My taxes aren’t complicated and I’ve had one employer the whole time so getting W-2s was easy. I pulled 1099-R, 1099-SA, and 5498 amounts from my Wage and Income Transcripts. Luckily, despite years of anxiety about how this was eventually going to bite me, I was actually owed a refund every year. My withholding was on point for a small refund each year before the child tax credit, and then the CTC adds on. I know I won’t be receiving anything older than 3 years due to the late filing.

I expect it to take a while to process everything and issue the refunds that are still payable, but is there any idea how long “a while” that may be? I mailed them in separate envelopes, but they were all mailed at the same time and the USPS received times are all within a minute, so they stayed more or less together. I know that if I had just filed this year, it would likely have triggered inquiry into the past years before the refund would be issued. Should I expect a bunch of notices about “return not filed” tax years as each year is processed separately? Or will there be any sort of tracking of the fact that several years arrived and are in process at the same time?

Anything else I should be aware of while waiting for all of this to process?