You can never be too close in my opinion. I too practice out to 70 yards, but would never feel comfortable shooting at a deer at that range. Too much chance for movement or miscalculation. Now, i've taken does beyond 40 yards, but perfect conditions and a clear shot. I normally take too long in judging a buck anyhow, so usually they are well within 30 before I'm ready to pull the trigger.

Practice long and it makes those 25 yarders a whole lot easier.