I’ve actully been wondering this myself. Inori & Tsukasa’s home rink is in Aichi prefecture (Nagoya specifically), but a quick map search showed that they’d need pass through the Tokyo prefecture to get to Niigata. It’d take 13+ hours or so to travel by train (including station hopping).
Driving from Aichi to Niigata would be a 5+ hour drive though. Seeing as they’ve reach Lake Suwa, they’ve only really driven 2+ hours from Nagoya. So I’m assuming they left really late in the evening from Nagoya, slept, then drive the rest of the way to Niigata and spend the entire next day dedicated to practice.
They’re on a time crunch, so it makes sense why they’d want to avoid traveling an entire day via transit.