your post
"seems" contradictory. You say...
"...
the company does not put down detailed SOPs in writing and striclty enforce their adherance",... and then you say...
"SOPs can never be set in stone, becuase people keep inventing new ways of f'ing it up, that's the nature of it!"
I have highlighted the word "seems", as your post encapsulates one of the many problems any industry encounters when it tries to document or script responses to dynamic and unpredictable situations.... whether that be a surgeon or the guy at McD's
Whilst I am skeptical about the mentoring program (as I can guess what type of person will go for it

), I sense what they want to do is pair people up so you learn/challenge the inevitable intangibles in a less threatening environment.
The best example I can give you is the CTWO brief; one guy can brief and you think he is a good operator, another and you think he is a shambles/tosser. One guy will subsequently pass his command course, the other wont. They both may say the same words, but convey a completely different impression.
I would hope under a mentoring program the environment would be such your mentor would tell you straight and direct what impression you give and how to correct. You can then mull it over and go back to the line and try it out. Sadly, the reality will be a 4 hour argument (in colour) about whether or not you should, or should not, brief the 07 engine inop or whether the MSA is based on the VOR or the airport; because we are "big picture" operators ugh: