MN, I agree that I find it niticky to call the 3 seconds on the barely touching the lane line scenario. You can choose not to see some things, and this is one that should be hard for a ref that is watching all the post play to notice
But there is another ansswer to this problem, and it is the one I give my players.
Dick Divencio, in one of his many insightful statements the book Stuff (a must read for serious coaches and players), tells players to set their own boundaries to avoid these silly violations. He suggests that the player's boundaries should be set 3 feet inside the sidelines and 1 foot outside the lane. That avoids the I just barely touched the line or I was barely in the lane type of violations, and eliminates any chance that the ref will think you are in the lane too long.
If you take that extra step out, there is no doubt that you have cleared the lane. And it really gives yo nice room to operate and attack the basket. Every one of my players knows where I consider the blocks to be (and I use a one-step away from the lane rule). You don't know how it's going to be called, so it's best to play smart and avoid any chance of the 3 second call.