I have over 4k in perception and when I gain perc while hunting, about 9 times out of 10 I will get better loot within 10 mins. Inside or outside radar, and it doesn't matter if there is green dots or not.
For example in Jason drone area that meant 15-40 ped, sometimes small global. We studied this with my discipline. She had under 300 perc and she got better loot maybe 1 time out of 20. So when u have low perc-skill, gaining doesn't tell u a thing. When u have higher perc, gaining tells u a thing
And yes, I'm getting good loots sometimes even without perc-gaining (and so did my discpl).