It does sound strange. Unless the shop working on the sheetmetal uses a CAD model to program their machines instead of punching in dims per a drawing. The few dims that you are putting on the drawings may be for inspection purposes only.
My company works this way on plastic molded parts and it...
I agree multi lead threads is good. Machinist Handbook has wide varety different thread types (light bulb etc..).
If you have a good machine shop they can offen design one or copy one for you.
Good Luck & Happy New Year!!
Mark
