I brought my horses home before my arena was built. Brought them home fall of 2019 and didn’t really finish the arena until late summer of 2020. So a full year without any arena. Had a small, relatively flat-ish area I could school in the grass when the ground wasn’t too soft (or hard).
It does slow down your progress. Without a doubt. But, my horse was sound and fit and everything was SOOOO much easier once I had an arena again. The hill work and not riding on perfect, level, footing really helped to teach my cocky OTTB that half-halts were his friend and that paying attention to a rebalancing was a good idea. Even with my arena, I still try to ride in the hay field at least twice a week when I can–both for fitness and his brain.
I do think that I sill rode a lot more regularly than some other friends who keep their horses at home. I don’t mind riding in the snow or doing walk-only rides when the footing was questionable. I also live on a gravel road, so utilized that for hacking when things were really wet.
It’s all going to come down to your priorities. I have friends who haul out a couple times a week even with an arena at home. I have friends who board for a few months in the winter. I have friends who barely ride even when everything is great.
To me, hauling out twice a week feels pretty doable–three if you’re close. Then if you can supplement with two creative rides at home you won’t be far behind. I know at least two of my rides each week are not intense training rides anyway as that gets mentally and physically too demanding for my guy.
But I absolutely love having my boys at home, so YMMV.