Yeah..freestyle is the foundation, well it should be for every m.c.
You have to first earn ur stripes in a cypher amongst ur peers..every m.c. that i know of personally started off as a freestyler and developed from there..
Wen i used to spit, i would freestyle to a track to get my delivery then once i felt the flow and timing was right, then i would write to the track according to how i feel it should be delivered..
The freestyle wouldnt make sense but it sounded good to niggas listening to it..if niggas responded positively to the bullshit rhymes but on point flow, thats the style i would use wen i write to the track..
I viewed my freestyles as a blueprint for the overall constrution of the music i was making at the time..