VirtualGareth:
Escuse my ignorance ...... but what is VEM?
Virtual Equipment Model.
In a nutshell, the gaming software models the performance of clubs and balls and defines a behavior for each, such as distance, precision, forgiveness etc. to help make the game more interesting/realistic.
You will find this to be a huge topic of discussion if you do a forum search on the subject.
The primary bone of contention among many top players is whether the clubs for example, follow a normal distribution in their accuracy i.e. the size of a circle drawn at where you expect the ball to end up inside of... independent of other factors such as terrain or wind, which could shift the circle, or enlarge the circle, or both.
Many players strongly believe that the club performance is influenced by the player's performance history as well. So as your ability improves, the defined accuracy is tweaked (e.g. make the size of the circle larger, or cause a shot to land outside the circle) to make it the game harder on an individual level at a given time. To support this there is a VEM patent by WGT available to the public that describes this influence based on a player's changing ability.
Having said that, it does not necessarily follow that a patented method is actually used. The nature of the beast is that companies try to cast as broad a net as possible to cover any possible future scenario and try to limit the competition to get around their ideas.
Anyway, I would say that it probably takes 1000's of rounds of play (or some well-controlled experimenting) to be able have a feel for what is going on... and even then there are arguments strongly for or against the influence of VEM based on player history.
-Keith