well - I think 'practice' is the better word.
The problem with mid-race join is the drivers who go out hot lapping and disregard other racers who 'get in their way' whilst driving about.
The worst offenders i can not stand are the ones which drive quickly up to the guy in front, then shadow them, or 'tail-gating' for want of a better word, forcing them into a mistake and then they crash.
There is no need ofr that type of driving and the fact that lap times can be gained by MRJ just make that problem worse.
I don't have a problem with MRJ who respect the rules but ones which join and hot lap and break the rules and affect other drivers should burn....