Depends on how packed the cruise is and when you go. We had the kids in their swimsuits when we boarded, had lunch, and then headed to the pools and Aquaduck --- no lines as people hadn't received their luggage yet.
We also went first thing in the morning -- no lines, and at late night (an hour or 2 before they closed) --- again no waiting.
Avoid Sea Days if you don't like lines --- my kids went at least 20 times because we planned it right and they loved it.