high load in a cell means that neighbour cells are probably highly loaded as well…
If that’s the case, then it means all frequencies are highly utilized, which means the C/I degrades, which leads to more drops.
I would say the increase in drops is about +30% to +50% compared to non-busy hours.
If neighbours are not loaded, then I would assume that one of the TRX which is usually not used during low-load starts to take more traffic during the busy hour. Bad luck : this trx is either faulty or uses a frequency which is “dirtier” than the ones used in the other TRXs.
Let le know if that helps,