How much enamel must be removed for bonding?

Removing enamel when bonding is done is a judgement call by the dentist. It's not wrong to remove enamel. The technique invoked by your dentist may have been more aggressive than done by the previous dentist but it may have been necessary with the materials currently used by the dentist. If you are happy with the results that is what matters most. When it becomes time to replace the restoration in the future discuss with the dentist your concerns about enamel removal. Do this before the work is started and you won't be surprised again.

Depending on the kind of tooth fracture it is and where it's located on the tooth, enamel should be removed in order to gain more surface area for the bonding to adhere to. Enamel removal is also important in order to make the restoration "invisable" so that you can't tell that the tooth was repaired. This tooth removal is usually done as a bevel of the surface vs. removing part of the tooth. Hopefully you won't need to worry about the bonding coming out for a very long time!

We do most bonding today without any enamel removal, but sometimes with chips or cracks, it is necessary to smooth the enamel.  In some cases, if a portion of a tooth is too bulky, then we will reduce that area until it is in better alignment.  If your bonding should ever fail, it sounds like there will still be enough enamel to bond it again.