The activity bosses should all scale to be completed in three phases, despite number of players. Three can take forever, solo, so requiring more is just awful. I've done my fair share of solo stuff, not for awhile now though, I just realized. Kind of fell out of this game a lot in recent months. Three is the magic number in gaming, I feel. If it requires multiples, anything above is way too tedious. Anything below might be too forgiving, unless its ultra hard, in which case it should be two, or one if they really want to go crazy with boss difficulty. I feel it should take one player around the same amount of time it takes three players to finish, unless rewards are far greater. Rewards aren't increased from solo to three, last I remember, so proper scaling should put everything in the same timeframe dedication, regardless of player numbers. If rewards are double or triple for finishing the activity solo, then extra time committment seems reasonable. Rewards should scale up for doing things with fewer others, if the time dedication is far greater. That might be a good way to incentivize more solo dedication.