Im about to try and coat my car for the very first time. Every where I read, the second layer of CQ UK 3.0 has to be within 60 minutes or the next day. But I can not find anything about why ?

What happends if I finish my first layer in maybe 2 or 3 hours, and then begin the next layer ?

I know there has been many threads about layering. But I still cant find the answer to this question. And I really would like to finish the coating in one day, without stress....