Some places require one whole blank page, to give enough space for the entry and exit stamps. 6 pages does not sound correct.
For Schengen countries (most but not all of mainland Europe), they just stamp when you enter and exit the Schengen area, not for each individual country; and they don't stamp Schengen or EU passports as these have unlimited right to enter.
And, as I keep pointing out and as Sam said, it is not customs who stamp you passport, it is immigration (passport control).
Customs = checks on goods, and whether you have to pay customs duties for your goods to enter a country.
Immigration = checks on whether you are allowed to enter a country.
At airports these are two separate processes.