Overload protection

Yes it is common practice, but not actually a requirement, a single device that protects against both overload and short circuit is permissible.

I prefer motors to have their own overload protection connected directly to their contacters, with the control circuitry protected separately.

the best approach is a function of motor size, and what it is doing.

The fundamental issue is one of starting and running currents. For all but the smallest motors, the is no single fuse or breaker value that is both high enough not to blow on start-up and at same time not low enough to guard against the windings being damaged if there  is a stall or heavy overload condition.  This may be adressed by soft starter circuits, star delta switching or nowadays the electronic speed controls, but the tradition is to have a simple fuse or breaker to protect the shop wiring that is  significantly ‘oversize’ for protecting the motor, and an overload trip that is chosen to suit  to the thermal time constants of the machine. Really big machines may have winding temperature monitors and all sorts of other fancy solutions as well.

At the other extreme for something small like a bathroom fan motor, no-one bothers, and there is a one-shot thermal weak link embedded in the windings instead.

Mike.

The other feature of this is that the short circuit protection (often a fuse) must be at the supply end of the circuit but the overload protection, i.e. the thermal overload, can be anywhere and is often built into a box beside the motor.