Lindsay,
We never had a schedule when DS had his tube. He started out at 18 hours a day of continuous feeds, and the nutritionist and g-tube specialist was very clear that any 18 hours would do just fine.
Generally I hung a new bag full of 24 hours worth of formula. If he got a midnight chest PT session, I turned it off 1/2 an hour before, so he wouldn't reflux during the PT, and then turned it back on afterwards, otherwise I ran it straight through the night. Then in the morning we unplugged it while he was down and playing, and plugged him back in whenever he was doing something relatively still, like riding in the car or going for a walk in the stroller (long walks in the stroller were our godsend in those days), or sleeping. We also kept it unplugged for 1/2 an our before each nebtreatment/chest PT so we'd generally schedule playtime right before those (but those weren't really scheduled either, our pulmonologist just said to fit in 3 or 4 a day, no less than 4 hours apart, so we worked around the rest of the day. When the bag was empty we stopped until bedtime. Some days if he was traveling we'd end up with 6 straight hours of no feeds, and he was fine. More typical he'd have 10 or 15 minutes on, then 10 or 15 off, all day except for naps (e.g. on in the walk in the stroller on the way to the park, off as he ran around for 20 minutes, on for 10 minutes in the swing (I just jammed the backpack behind him in the baby swing), off for more play, on for the ride home etc . . .
I've never heard of another family without a schedule, but not having one made a huge difference to our quality of life, because we could grab every minute of potential playtime as it came up. He used his tube for continuous feeds during the day from 9 months to 2, and was a pretty active toddler, so this schedule let us spend the afternoon at the pool (feeds during adult swim!) or go to a birthday party regardless of the hour.
At first I was really worried about not having a schedule, but once he started really eating, around 2, and I could see how toddlers really eat (e.g. one day lots for breakfast, lots for dinner and nothing in between, the next day grazing all day long etc . . . ) I realized that what we were doing was pretty age appropriate.
I wouldn't go to a "schedule free" life without asking, but for us it made a huge difference.