Yiannis1970:
I have to choose before the game a specific set and play with it? If so, what's the purpose of buying the bag? .thanks anyone who'd like to respond.
Forgive me if I'm not understanding your total query (I'm only on my 2nd cup of coffee), I think I get what you're saying as I asked myself the same thing long ago. But below is a little more info on the functions of the bag that make it worthwhile for me.
Briefly, yes, you can do it manually w/o the bag if you choose each club you want to change, drag it, check it and make sure it's the right one, maybe change your driver and balls, etc. etc.
This surely takes less than a minute, usually, for me. Or I can click one of four slots w/ the bag and I'm done. It's just so easy and w/ the free credits from the 'watch videos' it was an affordable bonus.
I'll use different clubs, balls, and irons for Blitz, stroke, streaming, and testing or daily preference (e.g. blitz = 4 wedges + the R1 3W @ 230yards) (e.g. Nike 85 slower meter irons w/starter balls for occasional practice - sometimes I'll practice w/ my proshop balls)
CLICK HERE for my examples of the functional convenience of the stand bag.