I don't think you should LST a plant that's in flowering it might stress it.
I don't know about flowering but I had a few skunks in veg and I had the light 400w two feet away, after they had a little growth spurt that made them stretch about 8inches I lowered the light to be 2inches away from the tops which haulted the stretch and now they are getting very bushy.

Note: not all lights can be put close to the plants (especially HID systems) although I can because I have a eurotech hood (like a cool tube) and there is little to no heat pm them.

Goodluck hope this helps
superskunk1 Reviewed by superskunk1 on . Does the stretch ever stop? This sour diesel is stretching way too much for my liking. It's already doubled and it's 2 days shy of finishing week 3 of flowering. Does vertical growth slow down or stop at some point in flowering? Rating: 5