If it’s the same in the US as in where I lived, the employer will try to push working hours count to as low as possible. Like, you must do this and that to prepare for work but who knows how much time you spend for that so we pay nothing.
To be fair, this is not uncommon in other fields, where you must get better to stay useful for an employer but that effort is only “paid” in rases (sometimes) or not being fired.