I've been chewing nicotine gum semi-regularly for a couple of months. I use 2mg pieces, and I found a single piece to be pretty intense at first; I'm a bit more tolerant now.

Did you read the instructions? You're supposed to chew on it for a bit, than 'park' the gum between your gum and teeth, let it sit for a minute or two, rinse, repeat. If you chew continuously you get the whole dose quickly, which can be a bit unpleasant if you don't like the nicotine buzz.