I can't believe someone is asking if it is "mandatory" when is there in the title...
Following up on lowering the life boats, during our last cruise, we stayed on the ship when we docked in Nassau, they did a crew fire drill, all the non essential crew and cast members participated and lined up on the starboard side, you can see servers, cooks, cast members as well crew members, they were right down our verandah, as we were getting ready to go for breakfast and to the pool, I started hearing banging noises and some kind of motor running, I opened the verandah and watched the show, they did the horn blasts and then watched how they lowered four of the lifeboats and also how they assign different roles to each crew member. What I noticed, it is not as fast or as easy as you think. There are a lot of cables and tethers that need to be removed etc...it took easily 15-20 minutes to just get the boat ready to start boarding and they were working as fast as they could, the muster station leader was with a horn adding pressure and taking time with a stopwatch. Once they finally lowered them, they turned on the engines and moved them towards the Aft, did some sailing and then came back and put them back.