I seriously doubt he had zero intention or ideas for, at the very least, Snoke
The dude left everything for the next guy to think about
Who is Rey Who is Snoke Why is Luke exiled Etc.
It wasn't his job to plot out the trilogy.
TROS wasn't just a bad follow up to The Last Jedi it was a bad follow up to TFA. Snoke doesn't somehow derail an entire movie he had planned in his head.