The way I like the weather to be is that
-one cannot for cerain know if it will rain or not (unpredictable)
-most of the 14 practice days it should pay off to practice dry, not wet, iow, the chance of rain should be 30% or less during our preperaion time
In my perfect world we would only know the % chance of rain for a track, e.g. 25% for Silverstone. Then we would have no further forecast. However, if the practice session is dry we know the qual and race will by dry, if the practice is wet then there
is a chance (e.g. 50/50) there will be rain in qual and/or race.
The logic here is that if we only prepare ourself for a dry race we minmise the time needed to be prepared for the race. I know we all are skilled enough to handle unexpected wet weather, we have done it before with great success, but here we would have the practice session to brush up on our wet skills.
Personally I do not like the thought of only one change in weather in the race, I do not like to be able to read the future, e.g if it rains at the start and stops after 20 min I would not like to know that it cannot start raining again, because there is only one change. I love the unpredictabillity.
And for those who are thinking, "if I do not prepare myself for a wet race I will crash", it is much easier than you think, as long as you have experienced wet driving at some stage. The secret is to do the race a little smoother and softer than usual, coasting is a good method
Btw, I apprechiate the work put down by Jonas, Reik & Co, if it sometimes sounds like I am negative to stuff you suggest, it is not my intentions, but sometimes I write so fast/to the point that I am in danger of sounding harsh or insensitive