Yes, your point is fully valid and I completely agree. Trains are arriving BT. But due to less traffic, blocking mainline for 15-20 mins won't be a big issue. Otherwise JRC handles a lot of traffic :-D
In normal days, PF2 and PF3 were equally used. Trains were brought on PF2 when a DMU/Army train was parked on PF3 (quite common at JRC).