Freestyling is a difficult skill but also a pointless one I'd honestly rather listen to full fledged written tracks. I used to think you had to be able to freestyle off the dome to make a living as a rapper. It gets even harder when you have to do it in front of people or record it. One of the reasons I kinda don't wanna be a famous rapper is the radio hosts like sway/westwood will expect me to rip something on 5 fingers of death( i guess nowadays it can be written but how am I gonna conveniently have 4 verses that match the beat right away?). If I can't come prepared I may fukk up.
The main problem arises when you can't find a word to rhyme with or start recycling shyt and then say things that don't make no sense or start rapping off beat because your mouth is too quick.