well one of the very first dialogue exchanges between Obiwan and Qui-gong foreshadows the way the Jedi decide to change their teachings...such as YOda.
OBI-WAN : Master Yoda says I should be mindful of the future...
QUI-GON : .....but not at the expense of the moment. Be mindful of the
living Force, my young Padawan.
Then in ESB, Yoda complains to Obiwan's ghost that "long have I watched".....Luke's mind is always on where he is going, not where he is.
which is kinda amusing considering that's how Jedi used to teach before they all realized their ways were not working. And I always thought it was unfair to Luke because of that--i mean, Yoda just watched him for a few hours before deciding "i cannot teach him."