Research is a bl**dy pain - pardon my Klatchian. You've found out pretty much all of what you ought to need to know, then suddenly some minor character whose existence you weren't even aware of yesterday requires you to know the finer points of American football, purely so that he can relate an anecdote that has no real bearing on the story. Well, it does explain his limp, but he could easily have just said it was a football injury.
It was worth it though: he's a great character, and might turn out to be more than a walk-on part.
And that's my point: it's worth it. The devil's in the detail, and if you don't do your research you can't put the little details in.
If you don't put in the time scrutinising maps and entering journey after journey into a ticket-booking widget until you finally work out that the only train route southwards out of Wisconsin is to start from Milwaukee and change at Chicago, and how long the various stages of journeys will take, you can't write a believable story of of crossing the US by train.
If you don't put in the graft until you know and understand all the details, you have two choices: don't let the reader get close enough to see they're missing, or make them up. If you keep readers at arm's length they won't engage, and if you make it up they'll call you out on it.
To some extent, making stuff up is fine: It's fiction, after all. I'm not going to look through records to see what the weather was like on the day a certain scene was set in - but I do make sure it's reasonable for the region and time of year. I'm not going to worry if the street I described for a certain setting doesn't correspond to a real one in the city; some writers do manage this, but usually only if the setting is somewhere they know well, and I don't think many readers will mind if you don't: since I needed to invent a building that fitted my story, I see no harm in inventing a suitable street to put it in.
So there's a line somewhere. It's hard to say exactly where it is, and it's probably one of those lines in the sand that aren't quite straight and have to be redrawn whenever someone walks past, and occasionally get washed away by the tide; but a good general rule is artistic licence good, laziness bad.
If altering or inventing something will improve a part of your story, or make something work that otherwise wouldn't, go for it. But if you're making up details or leaving them out, to avoid putting in the work, pull your socks up! No-one said this was going to be easy.