Stocks have evolved. The very worst artificial stock that I know of was Reminfton nylon 66's stock. That would/could change poi by a foot in an hour if one side got wet.
Some 'plastics', like nylon, will absorb moisture which can cause dimensional changes. (Anyone who has used a nylon tent in rainy weather has seen the 'wilting' effect that moisture can cause.) I don't have any idea if the "Nylon" 66 actually used nylon or some other 'plastic' but it's quite possible that moisture affected its stability.
And I wasn't intending to cast aspersions on any and every synthetic stock, but simply pointing out the fact that it can be a factor to be aware of. There are many factors which are affected when temps get cold. 'Correcting' one might be somewhat helpful, but it really isn't a make-or-break factor if there are several others which trump it.
