CPA credit question

i have a question regarding cpa offers.
if its an email-zip submit offer.
how many pages or screens if you like the user-visitor must fill in order to get a valid lead.
i understand that the email-zip is not enough and they must fill more data. but how many pages-data must they fill. 2 pages 3 pages.
how can i know that info
a friend of mine told me to look when the pixel is fired..(didnt quite understand that) can you please help me with this.

email zip submit fires on first page-that is why their payout is lower than a more complicated cpa

It depends. Some offers will pay on the very first page email/zip submit. And some offers want an entire 2-3 page registration. It all depends on the advertiser and network. Most of the offers I use (on Hydra for example) say "pays on 1st page email submit" or "pays on 2nd page free trial".

thanks for the answers will look for that info with the particular networks to see if it fires on page 1 or not

just want to inform.
talked to 1 of my AM and he told me that the offers fires until the 3 page. so the visitors must fill all the info of 3 pages.
the good news is that they do accept incentive traffic.
will check with other networks.