My preference is to know where you’re going, at least some signposts you can head towards, then veer off of when it feels right. However…
There is nothing to beat being stuck, back against the wall, blinking cursor mocking you…than to just let ‘er rip. Make it up, take a side road, kill a character, bring back a subplot with a different location, change the dialogue from third to first – just…get…keystrokes…down.
Will you use these in the final draft? Who knows? Most likely not. But…no great story was ever written without some of this going on. So whether you’re an outliner or not, release the shackles and just kill it with the keyboard…amazing things have come of this, give it a shot and show us what you come up with.