What are some possibilities could be causing this plant to droop faster, and more often, than the other 2 (same strain). Peep attached diary for more info!

too much light is possible... is it droopy the last 2-3 hours of light cycle? Cycling from perky to droopy is okay, but if it's droopy the entire time, it's a "tired" plant that can't take anymore light relative to your co2, temp and rh conditions. Better conditions = more DLI possible. i assume the substrate is not dry? Common sense, but sometimes it needs to be asked. Obviously, if it's dry, it is wilting as opposed to tired. So you can rotate these around? Try putting it not in the center for a few days... then once it recovers start rotating your plants around or raise/dim light a small increment and keep it in the middle... Rotating might allow you to keep light at same intensity, which is obviously great for the other plants not in the hottest spot directly under it. Looks like top leaves are showing some deficiency? and if any of those symptoms are in teh wrong location (the "mobile" ones), even more evidence it's the light intensity. so, observe and find out when the droop starts.. if it's just the last several hours, probably the light intensity... even if it handled it up to this point... it may have just taken a couple weeks before it added up to enough stress to cause droop. Sometimes it's about the last several weeks or even a month of time before a symptom is visible.