I think that is one of the key issues.
As you know, we were on Sky over Easter, and the ship was full, just under 4000 pax. For most of the time, the weather was kind, so there was little problem getting seats in the indoor venues during the day.
However, on the last couple of days, the weather changed, and trying to get a table in somewhere like the IC was nigh on impossible. We were just pleased that we had a minisuite, and more or less stayed there for two days !
But, regardless of weather, you are right - finding seats in a bar after 21:00 can be difficult.