Which random mechanic is the most annoying? (item spawns, hostile encounters, miss chance, which parts get hit, branch depths, hacking, etc.)
Traps can be pretty annoying for me. Just going about my business in factory, stealth-flight-ing around,
totally not currently running from ~10 different enemies at once because I'm kinda bad even with a good sensor array, but then I get hit by an ambush or chute trap. These ones are the worst for me. Chute traps are not quite so bad if you're flying or hovering, but on anything else? You're as good as dead, at least at my skill level. Ambush traps are unavoidable squads, which is pretty bad imo. Other squads are unavoidable because I'm bad at the game, but ambush trap squads are unavoidable just because RNG.
How much does your success rely on RNG?
Currently, I would say a large amount. Finding enough hackware, flight units, sensors, etc. to keep myself going is tough. I've only made it out of factory once in semi-recent times, with a flight stealth hacking build.
How do you plan around randomness?
Hacking for schematics for things I need, although that doesn't really negate randomness (finding a fabbie in these giant factory levels, whether or not I succeed at hacking it, whether or not I'm traced before I can print, whether or not I got pressed between two squads earlier and so they saw me and came after me so I can't stick around to get the printed item, etc.). I tend to be poor at succeeding in these plans, however.
How well do your builds handle things going wrong?
Not well. When I inevitably encounter squads in such a way they notice me, they tend to deal a lot of damage to me over time, especially if I encounter another squad on my way to flee, and am faced with an unavoidable encounter with bullets.