I worked for one company for a month. From the get go they had 100+ staff but no onboarding. Nobody knew how to set up the development environment or even get the application working on the company laptop. Nobody could show me how to VPN to client sites or show me how the software worked. I was meant to support it...
I was in my manager's office every day letting her know hey I really need assistance here, nobody seems to have time, nothing is working, I'm not learning anything and this needs to improve.
She'd tell staff to assist and they just wouldn't. And rinse wash repeat the next day.
A month in we are in a meeting and some difficult software issue comes up and it's assigned to me to fix. I mention that I don't have it running, don't know how to use it, have no method of finding who the customer contacts are to call them and will sound stupid not understanding anything, but also haven't been shown how to connect in. That I'm happy to shadow someone else and learn it.
It felt shameful but I knew it was the right thing, I had a year of extensive help desk experience under my belt including programming and other development, bug fixing, accounting, you name it, I was even team lead. I was used to dealing with multi million dollar clients and had no qualms about doing so... but this place was dysfunctional.
Anyway the boss stared me in the face in the meeting and called me a liar, to shut up and get to work. I was stunned. I repeated myself and she turned to my coworkers who claimed they had "showed me everything". I hadn't spent more than 5 minutes with them in the entire month and had been in her office every day. She told me to start pulling my weight and stop lying.
I walked very calmly to the office printed out a resignation and left my keys and walked out the door. I didn't get paid (a funny side effect of walking out of a job) and the move left me penniless and ALMOST homeless.
Luckily I got a job just in the nick of time shortly after, at twice the pay, and being treated like a human being. I removed that place off my resume and rarely discuss it because it's so humiliating.
I still remember the recruiter calling me screaming how unprofessional I was - he only cared about his lost bonus. I explained I was extremely professional but that after being humiliated and called a liar in a meeting and having none of the promised training, or anything remotely capable of making me a functional employee, there was no recovery.
Now I take onboarding very seriously.