What should the pressure be on a MIG regulator?

Most regulators come "pre set" to something..
but nobody says what it should be?

I'm not talking about flow rate.
Yes, I do understand the concept of choked flow.

I can get the proper flow rate with either lower pressure (10 psi)
or higher pressure (80 psi), but it seems like the higher the pressure,
the more the first blast of gas when trigger is pulled.
Is that good, or just wasting gas?