I was reading Matt Waldman's blog the other day and he referenced a former college/NFL player who said the vast majority of player development happens at the college level. Said teams don't really focus on development in the pros- sometimes they bring in player consultants and that's about it. Said it's on the players to develop themselves through independent study.
Don't know if that is true for every team or not, but it was true for at least one NFL team apparently.
I'm guessing this is not true for your ultra progressive teams like Seattle though. For example, JR Sweezy played his first ever down on offensive line with the Seahawks, so obviously he's developed with Seattle.