Can spending stability lead to a Mythos shock?

Bob faces a Mythos entity and has to make a Stability test or lose 7 Stability. It’s been a long day and Bob is already at -2 Stability. Bob’s player chooses to spend 4 Stability points in order to (probably) automatically succeed on the test, bringing him to -6. This means that despite the success, Bob’s mind is blasted.

But was this a mythos shock?

Here’s basically all the rules say on mythos shocks, and why it matters:

Each time you are blasted by a Mythos encounter or attack (when your Stability drops to between -6 and -11), your Sanity rating drops by 2 points.

Mythos skill increases from full study of a tome

7th edition Call of Cthulhu rules give two mythos skill increase values for each mythos tome: CMI (initial reading) and CMF (full study). The general principle is clear: you gain a bit of knowledge from a basic skim of the book, and significantly more from a deep dive into the horrible content therein. What is not entirely clear from reading the rules is whether the CMI value is contained within (ie. is a subset of) the CMF value.

For example, suppose a tome has CMI +5 and CMF +12. Jim skims through the book and gets +5 to his Mythos skill. When he completes a full study, does he then gain another full 12 points of mythos skill (for a total gain of +17)? Or does he gain an additional 7 points (bringing his total points gained from that book to +12)?