I've just been to Cambodia.
For the visa rather than fitting it on the first empty page (the other side of the paper from a page with a few stamps) they instead skipped that and fit it on a new sheet of paper.
For the entry and exit stamps....they skipped the paper on the other side of the visa and instead went to a new paper.
The trip took 4 pages of my passport (albeit the 4th could still be used by countries where I need a stamp but not a visa)
I wonder about this; is this standard practice? Are left pages of passports ever used?