I've been training JS for my guards over the past 3 weeks and here's all of the data i've gathered so far. The skill levels are in the number values instead of word values (respectable=7):
first 2 weeks: lvl 9 trainer, this week lvl 10
6'3" 19 YO PG-partial training 1st week, full training wk 2&3-JS pop: wk 1 & 3, JR pop wk 1, DV pop wk 2
JS–6 to 8 DV-6 to 7 JR–4 to 5
6'4" 24 YO SG-full training all 3 weeks-all pops wk 1
JS–6 to 7 DV-0 JR–7 to 8
6'4" 20 YO PG–full training all 3 weeks-all pops wk 2
JS–3 to 4 DV-6 to 7 JR–0
6'2" 23 YO SG-full training all 3 weeks-JS & JR pop 1st week, nothing wk 2, JS pop wk 3
JS–6 to 8 DV-0 JR–6 to 7
6'2", 19 YO SG-partial training all 3 weeks @ pg (wk 1: 29 min, wk 2: 30 min, wk 3: 32 min): pop during 2nd week
JS–4 to 5 DV-0 pops JR–0
6'5", 21 YO SG-no training 1st week, wk 2: 27 min, wk 3: 47 min), all pops most recent training
JS-7 to 8 JR-7 to 8 DV-0
Hope this helps shed some light on JS training for guards. As far as I can gather, the better skilled a player is in JS, the faster his skill increases (unless my 20 YO PG just had really low sublevels before i trained him). I might train for one more week and see what happens, or switch to pressure PG/SG and do some research there. Also, having a player play for more than 90 minutes will harm his stamina. Just so you know. Also, if anyone has an excel spreadsheet they use to do this sort of tracking, please send it to me (BBmail me first). I know this info is kind of messy but hopefully it has all the necessary information.