I tend to sharpen several at one time rather than sharpen as I go. After a few tanks, or I get tired, I swap the chain and flip the bar. When all the chains are dull I sharpen them at the start of the next work day.No, 8 cords before changing out the chain lol . I sharpen every 2 tanks of gas ish usually depending on the wood. I'm usually cutting oak/maple.
I said 3/16 because that's what my files are if I remember correctly. I'll have to go look.
The round files will be a different size than the grinding stones, I don't know why.