Agility is one of those things where you get what you put in. I know a few people that take a one hour class once a week and that's it. But it takes much longer to be proficient that way, and likely they won't be at the top of the leaderboard.
A very serious agility person likely trains every day, even if just for a few minutes.
And a lot of people fall somewhere in between. I take 2 hours of class a week, try to rent the building when I can (doesn't happen as often as it should), and try to train in the yard for like 15 minutes every day or two. I usually miss that goal, but that's my ideal!