if i were to weld for 2 mins straight, non stop, i would blow the circuit breaker or the welders thermal protection would kick on.

15-30 seconds max per bead for me


50% speed isnt to bad, as long as your getting enough material in the bead and the penetration is good, then you should be fine. i personally like to weld a little quicker, and with the max heat setting and a faster speed you can to.

but if 50% works for you and you have decent welds, then keep doing what your doing.