Verizon's throttling policy is very benign. It is tower specific only for towers that are busy. It works something like this. If you have been previously flagged as a heavy data user (I'm not sure of the criteria) and you are using high bandwidth on a tower that is busy at the time you are using it, you will be slowed down only enough to allow reasonable throughput for other users using that tower. I hope that makes sense.
Well you also have to remember that your sharing that tower with many other paying customers as well. They want to make sure everyone gets their fair share of bandwidth (slow data is better than no data). Its a pretty common practice in any sort of network. It would be pretty ridiculous to give all their bandwidth to one person on the basis of "they were there first".
I wouldn't even consider what's described above to be throttling. This is the nature of the medium - it's shared. If a tower is busy, all users on that tower are adversely impacted - it's unavoidable.