Honestly for a 1 lighter I don't think it matters.. What ever makes the cables reach for me I'd work on how you have the wings positioned and that for me is about Flat top or Manhattan Style gardens Flat will be open wings and Manhattan style needs penetration to the base of the colas so I close the reflector. (That's certainly a good subject worthy for some discussion)
I have taken it out and properly turned them daily before now and the Mantis AEG male fitting needs to be set close to the bracket and @ the base if possible. (I have burn marks in old reflectors that show me where I was right, if you drew all those 'imaginary lumen lines' like on the packaging from the burn marks you visualise maximising the reflectors potential)
In a 1.2x2.4 you have overlap and direct & indirect light what can be used to an advantage if you place the lamps as the manufacturer suggests. I prefer multiple Arc's of bulbs and not 1 radiant 'Shit spot' where they yellow out under it and look bigger then the rest. I much prefer the whole grow being Optimal. Making no exceptions..