Colliewood: This WGT rule of expiring a ball mid round due to the number of hits yet you can't use another ball in your bag is absurd. Let the ball expire and allow the use of it until end of game then it can disappear. This still allows wgt to cash in on us buying more balls.
I imagine WGT's way of things closely resembles real golf (which is it's mission, other than generating profits from ball hits). When your ball expires, due to hits, you can use another ball in your bag. If you have more balls then the one that expired, it will be replaced with the same ball, if not, you get a starter ball.
IRL, balls do "wear out", maybe because it got wet before, and you retrieved it from the water and continued to use it, maybe a slice in the ball, etc.. When that happens, you reach into your bag and grab another. If you do not have any of those nice new balls, you may have no choice but to grab an old crap ball from the bottom of your bag and continue your round.
The good news is that WGT provides the opportunity to buy new balls while still in game. On the real course, I doubt many stop their game and go back to the clubhouse for replacement balls.
I believe that golf courses should have people drive around in carts selling balls. I know there are "beer cart girls", so why not "ball boys"?
In the end, I am confident WGT does not care whether you purchase balls in game, or wait until the end, all they want is to make things easy and convenient for the members. They are very generous in that respect.