I dont think its 20..unsure i might be wrong about that, but one thing is for certain, if you had your provoke macro up, and you use ANOTHER macro before the last line hits, your current macro will overwrite your current one(provoke msgs) so you wont see the end of it.

A better way to see ability timers is to bind a key that has recast on it.

i.e:

/recast "Provoke"
/recast "Agressor"
/recast "whatever"


on one of your macro slots seperate from the ability.