How do you manage to last 30 years

Okay so my previous airline was No. 1 in the world by a huge margin in the first 10 years of the game. However, as usual, I am unable to keep up the airline for greater than 10 years as it would become too demanding and took a large break, not visiting my airline ever since. To my surprise it still managed to be within the top 10 from the trophy, but I don’t know the exact position. Anyways I see people who can manage the airline for 30 years which is about 4 months in real life, and you can imagine how much time you’ll have to spend. So I just came back from a huge break and wanted to ask how much time y’all spend on the game, and how you manage to keep up for the entire length of time. Thanks!

Usually summer is the time when I can devote a lot of time to the game seeing as I'm in college right now. It's my way of unwinding from the hectic school year. By the time we get late in the game world I can spend 8 hours a day just adding routes. Also I should point out that I only play open worlds so the opportunity for expansion is pretty much endless. But it can get pretty monotonous and mind-numbing so I will take days off where I only play around 30 minutes a day just checking routes and ordering planes. It all depends on if I have things to do that day or if I'm just not feeling it. I just really love this type of game and that's the only reason I'm able to keep playing it so much. 

Woah I checked your airlines and it’s amazing how you have 2 worlds playing and both airlines are within the top 3. Anyways I have a decent amount of time everyday, I used to be willing to play for 12 hours a day but it soon becomes meaningless. Now I am thinking maybe just spending an hour or two everyday, and I’m trying to come out with a plan where I would just mass add routes.
Anyways I just started a World in O1. I haven’t played O1 before, mostly played in O2 R0 and R1 (the really old worlds) so I’m hoping I can get to No. 1 (like how I did with O2 although I joined about 1 year late)

I don't think you need to spend more than two hours per day on this? I do roughly that many and still manage to adjust my airline(s) to a quite decent extent. About the lost of interest, it will come later on in the game once it becomes a cycle of replacing planes and refresh routes, so I'd advise always try to change something to keep it interesting or plan ahead your development? Have goals. don't aimlessly spam the heck off of the game. Just my two cents.

I'm convinced there are a few people who are using somekind of script or utility to do all their "grunt" work for them.

It doesn't take that long to manage a large airline. Spend an hour a day placing planes, buying new and used one's and re-pricing existing routes. Totally manageable if you have a system and process you follow.