I have often seen the Tur cited as giving exact word counts for each blessing of the Shemoneh Esreh. The arguments I have seen for being careful to adhere to the word counts include that this would presumably be as it was brought by the Anshei Knesses Hagedola as well as the word counts having Kabbalistic significance, while the argument for relying instead on a given nusach that differs from these numbers is the very valid matter of established custom.
I'm having trouble finding the exact counts for each blessing - I don't have a physical copy of the Tur and can only find sections on hebrewbooks.org. Is it referenced in the Shulchan Aruch? If so, which siman? Is it brought anywhere else?
Perhaps the sources deal with this, but how does this accomodate differences between Spring and Winter, or Sim Shalom/Shalom Rav?