RailFans don't miss their train. Why? Because they go to the station HOURS before the actual departure of their Train - to watch OTHER trains depart. - Prince Maan

Pick-Up get altered, by keeping low power Loco & increasing Rake length!
Kalka Mail-P-7 & ASR-KOAA-WDP-4 manage pick-up only & suffice for rake load!! Pick-up can be understood like:
1. Both train stop @ particular station. Long train will take longer time to cross loop line & pick-up when reach Main-Line
2. If Short Train dont have stoppage @ big/station with high curve. Then...
more...

the short will be having enough acceleration @ slow speed & its pick-up will be higher, as its already having certain frequency.
PS: For SLN. Evening Passenger towards BSB runs @ 60-80 KMPH, just after Daryapur crossing, while Shramjeevi Loco start accelerating only when it comes near the outer signal before Daryapur crossing!! But MPS is higher for Shramjeevi!!