Before going ay further, let me tell you that any time you are knapping flint, you must wear safety glasses.
Yes, I have done all of the methods you mentioned. What you do often depends on the circumstances. If you are at home and are cleaning your rifle or just fiddling with it and it needs some re-sharpening of the flint. I may use my flint hammer and tap along the edge knocking off tiny chips until I have it sharpened. Do not do this in the house, do it outside in the yard. You sure don't want any of those tiny shards of flint on the floor in your house. They are tiny razors. I also have a little brass rod that a friend gave me that I use to place on the edge of the flint and rap with my flint hammer to knock off tiny chips. The rod is a more precise method of knapping the flint while it is in the lock. If I am in the field and need a quick re-sharpening of my flint, I often use a method that my late friend Paul Valindigham showed me one day at Friendship. You cock the hammer and use your left thumb (I'm right handed so if you are left handed just use the opposite hand) to raise your frizzen. Then while holding onto the cock, release the trigger and ease the flint down to the frizzen. Move the frizzen so that the flint is just touching the heel of the frizzen. Hold the frizzen in that position with your left thumb and move the cock back to full cock. Now pull the trigger and let the cock fall with the flint striking the heel of the frizzen. This will knock off several small chips from the edge of your flint and it will be ready to go again. No, it does no harm to any part and it is a perfectly good way to quickly re-sharpen your flint in the field. A word of warning: Whenever doing any of these procedures make absolutely sure that you are wearing safety glasses. I tiny piece of flint popping up into your eye will do serious damage to it and will be extremely painful
:idunno: 
