[wallot]

No need to buy whole set, buy the most quality taps/dies you can afford as you need them. Once i broke what i though was a good tap in GA 7075 maxx bulkhead and quite heavy machinery was needed to get it out - i really did not expect that machine cut thread was so awfull that i should have started with the course tap and not the calibration one. Had a same issue with couple FLM made threads and had to get a new chassis brace.
Taps for hand use should always come in sets of 3. First being the course for initial cut the last being for calibration. For machine use you can have just one tap.