I was starting a new game, and looked into Jun's console, and saw a sympathy meter. I knew what it was (context clues) and wanted to see what was the most effective way of making it rise faster. this is still in low variable testing (sympathy per minute kissing).

Modules: Hypercame Left Arm 100%, Hypercamo Experimental Right Arm 100%, Hypercame Experimental Left Leg 97.23%, Hypercamo Left Leg 100%, Hypercamo Cat Ears 83.98%, Hypercamo Hair 100%, Hypercamo Striped Fluffy Tail, Hypercamo Eyes 100%, Hypercamo Sharp Teeth 100%, High-tech Hypercamo Skin

Clothes: Baggy Pants, Right Plain Stocking, Left Plain Stocking, Yaranaika Panties, Sheep T-shirt, Milf Hunter Hoodie

(ALL TIME BASED MEASURMENTS ARE FROM IN-GAME TIME)

I measured for some base information for 10 minutes each for head patting, holding hands, or kissing. head patting and kissing seemed to be the same in sympathy per minute (SPM), that being just under 2SPM. since kissing doesn't require moving the mouse around, to remove variables, I went with kissing. I did some math, did a 10 minute test, then a 60 minute test, and came to some conclusions. 

With this, I did a large scale test. if I waited about 5 hours15 minutes while kissing, I would gain 600 Sympathy (for an SPM of 1.9 on average)

if you want to calculate how long for sympathy, use (Sympathy wanted)*(1.9 or kissing SPM)=(required time to kiss to gain sympathy) this may be a little inaccurate, but it is very close to the actual time needed.

I would love to get some info from the Dev, telling me what are actual variables in her sympathy, and what drives it the fastest

BTW, yes, I did this at 5AM