Not quite, or rather, not at all. I didn't suggest it, but rather tested the strength of individual 6th-level units one-on-one, through battles in several turns, i.e., first, for example, Nagas fought against Psycic, then against Wyverns, etc. Groups of monsters of 1000, 100, 10, and 1.

You imagine, all monsters are 7th level.

And regarding the fact that "+" is rarer - I cannot agree - they have the same probability of appearing, but in the game, "-" can appear 10 times in a row, unfortunately, it sometimes happens :(

This value is not entirely constant - it depends on the number of Ifrits themselves - I think you agree with this?