question for bst and spam key setupFollow

i have a question about setting up spam keys for dps output. i seen people say to use 2 spam keys for dps 1 linked to spells the other to disc/aa?

what kinda effect dose this have over just doing 1 spam key for everything.

atm i have all my non burn dps stuff all linked to 1 spam key I can keep hitting hand have it fire off all spells/disc/aa as they refresh.

would it be more dps to have 2 spam keys over 1 spam key?