productivity of "regular" raspberry canes

[GrannieAnnie]

Just found a diagram warning not to just hack off the reg. raspberries too low to the ground. It says if you look at a long cane and visualize it divided into quarters- the quarter closest to the ground will have 15% of the  berry crop, the next quarter up to the half-way mark will have 40% of the crop, the  next quarter up will have 30%, and the highest quarter of the cane up to the tip produces 15%.  So based upon that I shouldn't be hacking mine off at knee height but just taking off the quarter tip.  How did I miss this little fact all these years? ::)

[GrannieAnnie]

[asbean]

This must be for summer-fruiting canes. The late ones (autumn fruiting) you cut down to ground level in the winter and they fruit on current year's canes.  Summer fruiting ones fruit on last year's new canes, the canes which fruiited last year willbe dead so need cutting down to ground level.

[saddad]

and you can't cut the wrong ones out by mistake!!!
:-[