Coach Campbell?

Coach, If you don't mind I would like to throw in my view to your question. Coach C will probably also deal with this.
As with any rules, there are times when you want to change-up because of personnel. It may be dangerous, however, when running a zone play. (Inside/Outside Zones) Take your example for instance. Lets say that you lock your guard on the 3 and send the tackle to the LB. It may work well. But what if the 3 slants out with the LB coming around to the A gap. Now you can't come off the blocks to pick him up. Also the steps that both your linemen take are necessary to match the blocking with where the back is getting the handoff. Getting to defenders to early is just as bad as getting to a defender late. However on plays, such as the option, you can adjust your blocking accordingly. I had probably the best guard this year that I have ever coached. So when blocking the 3 tech he didn't need a hand check, etc. when we ran the Inside Veer or Outside Veer.

note: Inthetrenches and myself were answering at the same time. Both very similar responses.