Tbh he doesn’t need to go to the floor 99 in one go, since he’s basically immortal he doesn’t have to fear dying while climbing the rest of the floors. Plus right now there’s no way he’s strong enough to complete the floor 99, he would be killed on the spot again and again and again. On the contrary, by climbing the floor normally he would slowly get stronger and once he reaches floor 99 he should be strong enough to complete it without dying too often.