I guess it all depends on who you are playing with and what the situation is. The group I roll with would call it an ace if it was from the tee into the basket in one shot. However, the difference is that it is not a money ace. We define a "Money Ace" as anything that affects the scores of our league events, match-ups, or tournaments. Anything done in "practice," whether during a fun round or throwing multiple drives for just fun or practice, we would still consider an ace. We look at it that in our group, to get an ace, any type of ace, is a big deal because they are so few and far between. In our group a few of us can routinely get it out to 360 to 400 but the majority look at anywhere from 250 to 300. Not too many ace opportunities in that range except on certain holes.
The only time our group had an argument about the validity of aces is when I set up a portable basic in a field, marched 350 feet with a stack of drivers, and proceeded to drain one with my Striker. I lobbied unsuccessfully for a "Field Ace" but had to settle for a "Nice Shot" and a grumble that I have yet to get a real ace with that Striker.
In three years between 15 people, I believe we have only had 2 "Money Aces" and 15 "practice" aces. I have 6 to my name and I would hate to have to give 5 of them back because I was practicing my drives from the tee box (not just dicking around but actually trying to get aces).
Maybe that can be your determining criteria: If a player is seeking to drive well, whether for money play or in practice, with the intention of either landing within putting range or seeking to get an ace and an ace occurs, it counts as a full and regular ace.
This should eliminate those lucky shots where a player is just horsing around, chucking for the sake of chucking with no care of the result, and one happens to go in.
Scott