For most MIG or MMA welding a 9-13 will give you the range you need. I'm reasonably sure (but it's not my area) that TIG is also fine in this range.
The lower shades seem to be more useful for plasma cutting.
Some helmets have a 'grind mode' where it can be turned off, in a fashion, so the same mask can be used for grinding without it going dark from the sparks.
Shades 5-9 are not much use for a high intense arc (mig, Tig , mma)
So if your using it for those processes 9-13 is fine. That's all I ever use 5-9 usually more suited for fuel gas cutting and welding or perhaps a bit of plasma cutting.