Yo man.... I'm really proud of you and this is a great thread... and imma let you finnish.... but..... Beyonce Had one of the greatest videos of all time!!

hahahhahaa......... no, just joking, but really. there are a few points you have wrong, and that you fail to mention. When one lands, on must land on the balls of his/her feet. that is very important and I don't see it here.
and the thing about the Decreasing the time of the landing? that is confusing.... I look at that and I am confused. so imagine a beginner just starting off looking at this for the first time. to have a safe landing you need to decrease the amount of impact, or force, absorbed.... and that is where the roll comes into play. but like you said there will be times where a roll won't be possible. so a good landing is a must... in that case there are a few points to remember.....
1. land on the Balls of your feet. (always)
2. resist the impact by collapsing to the ground absorbing the landing with your legs. (not your knees)
3. the softer the landing the better. (you have this right)
you don't want to be tense, but you don't want to be loose. this reminds me of a good Bruce Lee Quote:
"Not being tense but ready. Not thinking but not dreaming. Not being set but flexible. Liberation from the uneasy sense of confinement. It is being wholly and quietly alive, aware and alert, ready for whatever may come."
maybe he wasn't talking about parkour or landings, but it seems to apply.... haha. and one more thing.....
4. the entire landing will take as long as it takes..... some landings have so much force and momentum, that it can take minutes, to days, to weeks, to even years to just recover from... er.. I mean absorb the impact.....lol..... so make sure if you are in a position where a roll is not possible..... try to climb down a little before dropping. or don't drop, unless you know how to land with softness.
And forget about that equation you have..... the way you decrease the impact is simple..... you can't, there will always be impact, and you can't decrease it unless you decrease the height at which you drop from.