I found BigBazooka, Dynamite, Jet, Stimpack, and Tesla Helmet all in the same area so i don't think the area matters. But Jet plans were loaded by a tier 2 Doctor and did not show up on his Fix-Boy list so this appears to be a bug.
Also i use Lockpick 300% + lockpicks, Luck 10, Agility 9 and Perception 9 and i still fail 10 times in a row on some lockers. The heavily trapped lockers don't seem to be any more important than non-trapped lockers. Also lockpicks break sometimes so make sure you bring several sets.
I know of one blueprint available in a town via a "quest" but this is not a spoiler area - just saying not all BPs are only in random lockers. One last thing: the only encounters where i find lockers seem to be always with critters or NPCs, and never in an empty grid with no potentially hostile life forms. So entering and re-entering the same "triangle" over and over to hurry things along does not seem to work for me - i have to actually cruise an area for hours to find actual encounters in order to find lockers, and even then only in some of them.