They varied. The one I currently work for is fairly large (~300 people in software and product, which constitutes maybe 1-2% of the total number of employees). I've worked for larger and smaller companies, though.
The company I work for now actually has fairly long tenure times, 4 years or more. There really isn't an expected ramp-up time. Each project handles onboarding their own way. "Hit the ground running, learn as you go." is pretty popular.
