I think it is because you do not understand the difference between a very peaked distribution around 10 minutes intervals, and an exponential distribution with AVERAGE 10 minutes.
i do understand, much more then you think
my maths are only simplified not due to not understanding, but just to try getting to the point in a way even a layman can understand easily.
i use layman analogies to tone DOWN technicals into average guy speak. however it seems you try to grasp things at a laymen and try to abstract it into technical babble, while still missing the main points
yes there are more variables, but my posts only explain parts of them because the parts i mention are trying to show where your parts fall flat and it would end up taking a whole book to explain how the other parts interplay aswell..(which then just sidetracks the point)
you some how think there are only like 2 mechanisms of bitcoin and that non-mining nodes play no part in any security, bar being a data backup.
there are over a dozen mechanisms that all interplay each other. where nodes and pools have a symbiotic relationship not just for data backup, but for security purposes and data validation, collation and formation.
bitcoins symbiotic relationship, the fastest first, the orphan consensus, the propagation, the relay the tx validation, the block validation, and all the others all have a part to play.
you keep thinking that its only a pool is master.. node is slave game. where if a pool only gets a block every 6th block its average solution must take 60 minutes to find.. is RIDICULOUS
your maths of statistics has not looked at the context of where the numbers come from, nor (it seems) have you run scenarios either using algorithms, or paper or dice or just your mind.
the short and curlies of the part you try to suggest is that if there were 20 pools of say 5% (where the average pool only gets 1 block every 20th block) in your eyes means a pool only finds a block every 3 hours 20 minutes..(wrong on so many levels of understanding the context of numbers)
when the reality is they find block solutions much faster, but are IGNORED/GIVE UP as soon as a winner is found. and they all start again.. the hashtime does not add up on the next round. it starts at 0 again.
just look at the times of orphans where a runner up actually does get to win because the fastest first cheated or done something wrong, or other unmentioned reasons
https://blockchain.info/orphaned-blocks465722
Timestamp 2017-05-10 08:19:11
Timestamp 2017-05-10 08:19:10
ONE SECOND DIFFERENCE
464681
Timestamp 2017-05-03 18:55:39
Timestamp 2017-05-03 18:55:46
SIX SECOND DIFFERENCE
463505
Timestamp 2017-04-25 23:15:20
Timestamp 2017-04-25 23:15:22
TWO SECOND DIFFERENCE
not hours apart
much like olympic runners, having to run 100m..
just because linford christie or usain bolt win the majority of races, does NOT mean it takes 20 years for someone else to run 100m because they only win every 4th Olympic game
please look deeper at the numbers and look at the context of the stats.