well I’m trying to fill a 5x5 space as fast as possible so would you suggest maybe tying them down so that the growth doesn’t slow down at all even by a couple of days?
I'd top at least the main stem then tie the rest. I don't think it really slows them down and if you're looking to fill the tent, having a single main cola and a bunch of shorter ones won't do what you want; beyond it being a pain to deal with one cola that will be either way taller or just wonky and bent and extended out.
I've done the 'just tie down' gig and it wasn't really for me.
Here's a plant from a few grows ago, you can see that it has one big stem that's been trained down but still is taller than the others, etc.
Now here's one that's been topped (a few times) and also LST trained down:
Lower, more consistent spread and pretty even height. In this case, since i knew it would stretch (heavily sativa), instead of putting 4 plants in my tent, I've only done two and given them more room for spread and then stretch.