It's a little bit of both. I have heard of AVs (especially the green ones) blooming continuously for well over a year. I have one that blooms continuously for about 9 months, when I finally repot and chop off the remaining flowers. On the other hand, I have one that blooms ONCE a year. However, at any given time there is something blooming.

Additional light will help. Also, in some cases blooming frequency is genetic so you might have more frequent blooms if you grow different varieties.

From my understanding essentially all AVs require a rest period when they don't bloom. This period may be short or last for months depending on the plant and conditions. The only continuously blooming varieties I know of are from Optimara's Everfloris line.

It's different for different plants.

If you get enough plants, after awhile you'll have enough variety to have bloom all year long.

Of course, if you want this, you'll have to take excellent care of your plants, making sure that they get enough light, water, and food.

I've got one violet (Starry Night Blue) which has been in bloom now for more than a year, but that's just that plant.

Best of Luck ...