This is the best opportunity you have to set your people up for success, bar none. Plus, many of the things your company should do to build a great onboarding experience can also be leveraged to make it easy to do things like "move people between teams", "expand into a new office", and "hire great people".
Done properly, this is cheap as hell.
I had one HR drone complain about developers being bad at logging time. We told her that the system sucked and made it to hard to correctly enter your hours. She the proceede to demo how easy it was by entering her hours for the week. Basically: HR stuff = 37 hours. She had no clue that the average developer had more tasks during one day, each requirering it’s code, that she had during a full month. HR, especially in large companies, are clueless about the actual work being done.
Personally I no longer participate in personality test. If one is required during the interview process I decline and leave. It always HR that require the test, never the people you’d actually work for.
For onboard: The people I’ve onboarded for different companies all get the first day to settle in, setup their computer, find the coffeemaker and just look around. Day two you get a real assignment, ideally something you can fix and have in production before four o’clock. After that it’s just progressively harder tasks until you can manage on your own.
I do this as well. I've had companies send me online personality tests with seriously invasive questions. With no explanations as to the purpose, no guarantees regarding data protection. Just a quick "fill this out to see if you're a match". I'm sure it's designed to carefully skirt around anything that's overtly illegal, but fuck that. They go on my shitlist.
The company I work for has grown from 3 (founders included!) to over 30 in the time I've been there. When you're tiny, and someone new joins, there's no need for formal onboarding, osmosis sort of does its thing. This worked reasonably well until we reached ~10 butts in seats. Unfortunately, this 10 people mark was also where pressure started to ramp up. More customers, tighter deadlines, bigger workloads, and a struggle to survive -- because at this point the first round of financing was spent, and we needed to prove our worth to future investors. Everyone was stressed and overworked. Basically, there was no time for onboarding. Which is stupid, because it's an activity that pays dividends in the sort-of-short term.
Once we reached the 30 people mark, we were able to breathe a little easier in regards to workload. We're still growing. Onboarding is starting to become a thing. Where things aren't automated, they're being documented. We at least try to make time for introductions. It's far from perfect. It needs to improve. But it's hard. And I should probably take a moment to apologize to hire ten through thirty for what must have been a shitty first few months for them.
For the most part, my employer has treated people pretty well. Workload has been high, but flexibility has always been high as well. Along with $$$. Working here has definitely given me an appreciation for the hard work it takes to get a company off the ground.