Almost never.How often do professionals break either the tank or base? Which is more common?
Once you break one, you don't do it twice.
There is a learning curve.
You can be too tight, or too loose.
I had a customer the other day where the plumbers had the tank on too loose.
The customer took a screw driver to the tank bolts and fixed the leak.
Not my plumbers, their plumbers.
I broke a bowl in the early 70's
I prefer to supply the fixtures.
Then it's my fixture to warranty.
If someone else supplies fixtures, then there is no warranty.
It's all time and material at that point.
I can't tell you how many times I've tried to install homeowner supplied American Standard and Kohler and had to schedule a second trip until they had a non-defective bowl or tank.
A second note: Once someone has had a tank or bowl sitting in their garage for a while, waiting for installation, a lot can happen to it.