Hi Dikshi,
We are not using the B1 frequently and we are using the C1 Screening (Periodic Screening against Delta SPL Files for all the BPs in the GTS System) .
and about Blocked records, we use to get around 0.01% (1942 blocks) the compliance team and Business team validate the BPs and release them if they found the BPs are good and remaining BPs moved to Negative list.
hope you are clear now.
Thanks,
Srinivas Yellampalli