if "coming later" would help, I would, but it doesnt. unless I start to log on maybe at 6 in the morning but Im afraid I have to play during the most crowded times, being EU timezone, when its afternoon here, japan has its main playtime, bahamut server reaches more than 4000 people overall sometimes, abyssea la theine is 100+ then (of which about 20 are ninjas) and misareaux (talking about timed spawn NMs, example gukumatz again) even reaches 200 sometimes. In the evening it gets better with around 2.500 - 3000 people online depending on day, thats EU maintime and america already coming in.
I was even talking about this evening time because thats when I try to work on my kannagi, I dont even start going into abyssea when I have the afternoon free to play. Therefore, "coming back later" is not an alternative and if you mean 20min-40min by later, your server either has less players or you have not tried to camp these NMs a few times yet. There are already groups waiting, gukumatz is being camped by several people, several parties even, when one leaves it doesnt take long for the next to join the competition. It does not get any better unless you log in far away from the main play times EU/USA/JP but that would probably be in the early morning for me and only during weekdays because weekend is always crowded.