Regarding practice, I can only speak for myself and on what I typically did before each event.
I tend to play the game every day for my lunch break, spending 40 minutes on the Dailies. If I have any time left I'd pick one of the Stages from the upcoming rally and run it a few times in Time Trial. Once I start the rally I do it all in one go however as part of my stream.
The exception was the Lancia Stratos section as I knew I was very quick on both Scotland and USA and sweated it out. Got some World Records (which I've never had before) but really that class was an anomaly.
Realistically, if you have two weeks to do a rally that's two weeks that people can practice in, and you can't police it either. One way to get around it is to have a one day rally, where the club is only open for a single 24 hour period.
That being said, practice isn't a bad thing. Sure the fast people will dial in their settings and so-on but for the slower drivers it is a useful way to get used to a car/location before you do it for real.
Besides, although real rally drivers only have the recce and shakedown before the main event, they're constantly reviewing the onboards and memorising the course as much as they can beforehand