I've read that if you want to remove a certain percentage, say 10% for example, of the total original weight you would remove 5% from each side of the limb (very slowly and carefully). I'm actually in the process of doing this for the first time and it's worked great for me. I've removed all the weight I wanted and am now going to start finishing it up. This is on a recurve but discussion I was following talked about both recurves and longbows. I'd be reluctant to remove more than 10-15%. I'd also be interested in what others do, I have a few more bows that are a bit heavy.