First of all, I'm a high handicapper. Currently I float around 20-25. I do NOT count penalty strokes when my tee shot goes out of bounds when practicing (I count all other penalties, just not that one). I don't count those because they inflate my handicap. When practicing, I've got my driver out every hole except for par 3 holes simply because I can - not because it's the smart play. If you slice 50% of the time and the right side of the teebox is out of bounds (and the subsequent 250 yards are also out of bounds to the right) - the intelligent thing to do is take out your 4 or 5 iron and put it on the fairway. That's exactly what you would do during competition play. But when practicing, every time, without fail, I'll sacrafice 2-3 balls to the right lateral hazard. Technically, that's 4 strokes - tee out of bounds, drop, tee out of bounds, drop, etc. But that shouldn't be factored in to my handicap. Basically, if you take a risk during practice that you wouldn't take during competitive play - I see no reason to rack up stroke and distance penalties. You're better off (in my opinion) just saying to yourself "lesson learned - don't do that," dropping another ball and practicing the safe and logical play.
Expanding on that theory - is it technically "sandbagging" when you make stupid decisions (i.e. hitting the shot that has a 50% chance of failure)? Like if you have strokes to spare, you might as well just go banannas and screw around - you're not intentionally dumping, it's just that you're level of risk aversion went down.
Or maybe I just practice wrong and you're supposed to practice like you'd play in competition. But then how on earth would you ever figure out how to manage that driver? You practice to get better. You certainly count every single penalty under USGA rules during competition play, but I don't feel there's much need to be anal about it when you're practicing. Really, other players would prefer you had a low handicap anyway Personally, I'd prefer to not play with the 34 handicapper that just makes the smart play during competition play, shaving off 10 strokes automatically because he isn't slicing in to the weeds out of curiosity.