We don't really have a season here in Texas. So we ride whenever the weather is halfway decent, which is pretty much year round. Even in winter we'll have days when it's in the 20s one day and 60s the next. Only reason I haven't ridden the past few days when it's rained steadily is because I don't trust drivers.
I didn't expect to get much use from a Cyclops trainer a friend gave me, but after an injury earlier this year followed by an unrelated illness, I ended up doing more indoor spinning than outdoor riding. And it really was pretty good. Kept me in good enough shape that my average speed is the same. My stamina is down a bit, but that's due to illness, not lack of conditioning.
For me the trick to enjoying the indoor trainer is to skip the stuff that just makes me with I was outdoors. I tried a couple of training videos from GCN's YouTube channel. But it was boring.
So I switched to binge-watching TV series I'd been meaning to watch anyway. I watched all five seasons of Orphan Black (a delightfully weird sci-fi series that has more in common with David Lynch and the Coen brothers style than with sci-fi), basing my workouts on the approximately 40-minute episodes: one episode for HIIT or FTP training; two or more episodes for endurance training. I set Wahoo Fitness on my phone to give me audible notices every 3 or 5 minutes, my cue to either sprint at maximum effort for 15-30 seconds, or to stand and pedal for 60-90 seconds to improve my climbing strength.
Works for me. I don't get bored with the indoor trainer. Only problem now is I'm out of Orphan Black episodes and the next series I'm watching now, Expanse, isn't quite as compelling. Not bad, but a bit too thick on the familiar tropes.
The indoor trainer has also been useful for warmups before an outdoor ride. Between the injury and illness this summer it was taking me longer to warm up, and that was harder during our recent hot summer. I found the transition easier if I warmed up indoors for 15-30 minutes before heading outdoors.