It's really not that difficult. Once you have the tanks cycled and plan the fish population. Then its just the maintenance and i do this weekly one day per day. this gives me time to also watch the various tanks and make sure all is good in fish land. It also gives me time to think What If i... (this usually costs money)
Anyway if planned right and if all goes well it's like looking after one cycled tank but doing it every day.
i HAVE 4 LARGE TANKS UP & RUNNING, AND SPARE TANKS FOR EMERGENCIES, PLUS 4 CHILDREN FROM 2 UP & A HUSBAND, IF i CAN MANAGE THERE IS NO EXCUSS!!! mIND YOU WORKING OUT THIS SITE , THATS ANOTHER STORY!!!!!!!
It's not so hard once tanks are established ... depending on what you consider "hard", I guess.
I currently have two tanks, a 46g and a 10g. If I only change the water (which is done weekly), I can get them both done in about half an hour. If I start messing around with the plants, it can take longer.
I don't find aquariums to be much work in the first place. I use a python for water changes, so that only takes a few minutes. I need to do some algae scraping every now and then which also takes a few minutes. I stagger filter cleaning so that I'm never cleaning all of them at once, and each filter only takes a few minutes. That's about it really...