Node gives the buff not per hit but....well...randomly?

Most often it gives the buff not "per hit" but "per enemy hit". This further seems to count especially for rage based abilites (wrath of baäp...whatsoever). And sometimes the buff appears not at all.

-> one enemy + x hits = one stack
-> two enemies + x hits = two stacks
-> three enem......... and so on till 5 stacks

This behaviour is most often observed in boss fights due to the low amount of enemies (1-3).