erchin 2b -- age of chinuch

the language of הגיע לחינוך as opposed to the other more specific languages first is used by shofar in our sugya. What is this age? Rashi quotes the gemara in Yoma to tell us ages. However, Tosfos attacks Rashi and says - what are you bringing in the gemara there -- that talks about fasting.
What is the hesber of this machlokes? It seems to be that Rashi is saying that that age of chinuch is across the board something objective, an age where we engage our children in all mitzvos, while Tosfos says there is no such thing as a generic age of chinuch and you need to examine each mitzva.
One problem with this explanation - in our gemara we see that each mitzva had specific requirements for the katan's chiyuv, sounding a lot like tosfos.