.. in a nutshell .. there are NO guarantees .. it is all probabalistic.
History suggests that the rules are reasonably OK as we don't have aircraft falling out of the sky day in day out.
What we would like to think we are pushing here is the VERY real need for the pilot to use his perfectly good Mk1 brain (tempered by a bunch of real world experience) when applying the rules as published in SOP type requirements.
The real danger is when the operation becomes blinkered monkey see - monkey do. If you see a reasonable need to insert a bit of conservatism then you should be prepared to do so .. and then argue the toss with the Chief Pilot a day or two later. While we all know of the horror stories associated with "difficult" companies and Chief Pilots .. in the main, most end up being fairly reasonable if the pilot's reasoning is logical and arguable.