Hello!
Regions page on mydx.eu was looked a bit, to get some stats.
For each Rayon, there is date and call for last confirmed QSO.
This QSO is either uploaded to mydx, hamlog or LotW,
as well as direct QSLs scanned (maybe even some via buro).
Now, assume some necommer starts RDA, and never miss one.
2500 since August 5th, 2020. 14 months of activity.
2000 since Jully 17th, 2021 (3 months)
1500 since September 6th, 2021 (1 month and 1 week)
1000 since October 2nd, 2021.
So far, 2425 RDAs were QRV and confirmed in 2021.
RA9AJ with 2268 is close: he only missed  157 RDAs in this year.
We wait Gena (and some others) to upload more LOGs, there are RDAC contest LOGs waiting, and three months of activity.
That would indicate RDA 2500 can theoretically be done in one year.
And on my side: I started  RDA hunting after RA3R spam in November 2020 with standing of some 700.
After checking paper QSLs, LotW, registering to HAMLOG and making QSOs, I come to:
2067 confirmed. 1957 confirmed in 2021.
I have 18 RDAs not QRV in 2021: 4 out of 100 rarest.
376 RDAs were missed in 2021: 4 weeks of vacations in 9A, QRL, sleeping, bad CONDX, QRL. Hunters excuses ...
Thanks to activators and authors of excellent support software, RDA program is fun every day.
73 gl, CU in the next pileup
Iztok, S52D