I think its just a mather of habits, a couple years back when I started doing some (lets call it artistic) pcb layouts I used Eagle, and every time I used something not in the base libs I would search back and forth all over the internetz no find it, one day I bit the bullet, and started making my own footprints, the first one took me like 30 minutes, I was like:
Dude, half the dimensions are missing from the datasheet..
After some tries it all clicked together, and using eagle or altium I can churn almost anything in 5 to 10 minutes, simple things like soic's, qfn's, tqfp's, and chips with thermal pads are really a walk in the park.
What I recommend it to ALWAYS print the footprint and test with the real component, more than none the footprint is designed/calculated for automated assembly and soldering in ovens, so I always add 1mm to the pads so I can easy drag solder them(in case of leaded buggers).
Just my little and humble opinion, really, take a bit of time, and just bitch around until you can get something that almost fits the desired sizes when you squint really hard, after that, you can only get better.