Is there exactly one healing/revive/save crystal per level?

I've only delved down into level 3 so far, but both the first and second floors had just one healing crystal each. I'm wondering if I can always rely on finding one on each level.

So, are there any levels without crystals, or are there larger levels that have more than one?

If there are any deviant levels that ruin your perfectly good yes/no answer, please hide the list behind spoiler tags to maintain the surprise for those who don't want to know exactly what to expect.

Solution 1:

Every level had exactly one or zero crystals. Details are below.

Levels 1-10 had one crystal. Levels 11 and 12 have no healing crystals. Level 13 does have a healing crystal, but it's in a secret area so might be missed, unlike the others on levels 1-10 which are almost impossible to miss.