Veg time- Scrog and LST

Hey guys, first post here. Been reading non stop for weeks now though!
Well to start things off- iv'e read pretty much every guide/diy/tutorial I could find on both these methods, but couldn't find much info on veg times.

I am aware that Scrogs require more veg time than a standard grow- is there a specific reason for this? I was assuming it just takes more time for the new arms to grow out and fill the screen.

Would an LST grow also benefit from a lengthened veg time too, for the same reasons?

Reason being, I am stuck on an 11 week time restriction- starting from rooted clones. That will leave me with only 2-3 weeks of vegging at the most (though I will be benefitting from hydro), so i'm wondering what method will get me the greatest yield/results based on that time frame.

I have thought about doing a SOG, but this is my first grow and I don't have anything to take clones off of- so purchasing 20 clones at $10+ a piece doesn't seem very economical.

My grow is in a 2x4 ebb and flow tray (though the actual area I can use is unlimited i.e. the screen can be much bigger if needed). 400 watt hps, with a couple cfl's for support. Planning for 5 or 6 plants since I dont' have the time to veg them very large.

Hoping to here from some experienced members, opinions on what style grow would best suit me would be greatly appreciated.
Thanks!