SAP has (or at least had, back in '98) a policy where the first 3 months after being hired, you'd be entering a full-time training program: during this time, you would get your full salary paid and receive a free set of training courses 9-5; people usually just checked emails before and after, so this wasn't really on top of another job. The process got you certified in SAP basis, ABAP, effective teamwork and other modules.

After that training, we would maintain monthly lunches with our training group and exchange anecdotes about our respective departments. The company benefitted enormously in the sense that employees that started at the same time, but would work for different departments, already got a wide network across different functions and departments from the beginning, something that normally takes decades to build, and employees already had valuable contacts and information that they could task about with their co-workers in their own departments.

Back in the late 60s/70s, when I was in university, I knew a bunch of IBMers (those were the days when your System/360-67 came with a flock of IBM staff). The standard for onboarding was that during the first 6 months, a new hire was flown here and there for courses. The goal was to make them feel valued as an IBMer, so that they'd want to stay forever.