I am actually both, I sometimes pre-plan things and other times I just do it. Like I sometimes make lores for some RPs, none I have ever got to use but they are there through planning. If I am over excited I do go bam, here it is lets do it XD. I guess I am 60% spontaneity and 40% planner. I feel random when I do things so time to time I plan things and at other times I don't, I don't know why though. My brain likes to do whatever it likes to do at the time and I can't control it.