I can sharpen the teeth right on my cutter wheel with a 4 inch angle grinder in about 15 to 30 minutes depending on how dull they are and how many teeth I actually sharpen. I never try to sharpen them completely sharp. I just sharpen them until they have a small radius on the cutting edge. My grinder has a 60 horse power diesel and it grinds very well even when the teeth are a little dull. Trying to make them like new again just takes more time and wears the teeth out faster. I can usually sharpen the teeth 3 or 4 times before they are no good. I tried nearly a dozen types of grinding wheels before I found one that would work on both the steel shank and the carbide. For anyone interested they are made by United Abrasives, Sait Grind, Part #20017 for a 4 inch angle grinder. The wheel is actually made to cut masonry, stone, and concrete but it works really well on the carbide and steel too. The wheels cost me $1.60 each and I can sharpen all 32 teeth on my wheel with one grinding wheel. Oh, by the way, I wear a respirator, safety glasses, and ear plugs when I sharpen the teeth. There is a learning curve in sharpening the teeth this way. It takes several times before you will get good at it but it's definitely worth the effort to learn. Taking the teeth off the wheel to sharpen them is very time consuming and this way its easy and fast once you learn how to do it. Wheel maintenance for me is no problem any more.
Another trick that some people may not know is this. If you use the teeth that you have to set with a depth gage, set all the teeth in the crosser pockets about 1/4 inch deeper than the lead teeth. These teeth are only needed to cut out the center when plunge cutting and when sweeping to the side they do no cutting. Setting these teeth deeper eliminates the drag on the stump when sweep cutting and it will make the grinder cut easier. Some of the vermeer grinders have this trick automatic by the bolt pattern on the cutter wheel, but some grinders do not.