If I would find this sort of pushback so irritating as an IT consultant, I presume a legal consultant would find it just as irritating. Why would you want to annoy an important consultant in this way?
Exactly. Experienced business people write this off to the "cost of doing business". You look at the total value and make a decision as to whether to continue the relationship. If you didn't know the way attorney's billed then you can be thankful for the lesson that you have learned. Read and understand before signing anything.
You are of course free to negotiate the fee down after receiving the bill and many lawyers will discount in order to continue the relationship. From my experience lawyers tend to be willing to accept whatever they can get that is reasonable - they aren't going to pursue an action against a client unless the majority of the bill isn't paid or there is something else causing animosity or problems.
On second thought, I think the more important issue is the one 7Figures2Commas raised: If you have a lawyer who does the worst of this stuff, you have the wrong lawyer.
With that said, my blood pressure would definitely climb if a client challenged a 6-minute incremental bill for a phone call that was only 2 minutes.