this is my ship
http://coriolis.io/outfit/asp/25A5A5A4E4A5D5C0s0s2424--0j---054b2i0m2t242f.Iw18WQ==.MwBj48EZLYCYRA==
i have had sessions where the interdiction rate was normal (the first one) then it seemed more frequent, then normal but i met an instakill viper 3 and barely survived with 30k repairs. i saved and quit at the station. very next session i made a jump then had 3 expert level npcs (and one mostly harmless who may have been a late arriving wingman for one of them) in one system in 5 or 6 minutes. and i had a another session normal and another seemed higher rate.
breaking them down, i had in the first session tried doing some deliver data and deliver cargo missions to see what the AI was like and i got one harmless guy in an eagle who died when i looked at it. the master npc with the bugged weapon was after the soontil relics i had for an engineer and i was on the way to maia to get meta alloys for another engineer. the experts all spawned in same system while i was flying around empty from point to point detail scanning. there may have been a 4th interdiction but there was no radar blip and it was an instaescape one. no cargo or missions. nor for the last sessions before i found i didnt want to play and if i clicked play i couldnt bring myself to launch my ship. so i decided to hold off on playing.
i dont know if tthats enough for you but it seemed to me i had more interdictions in at least one session than normal, and that they all had the same level pilot expert, and im competent. they had different ships. vipers eagles and a vulture i fled after i crashed into him and his shields lived and mine didnt.