Remember, a fuse can only protect the circuit after it.
Anything before it has no protection.
You are aiming to protect the wiring as much as the connected components.
It will do that job very well if correctly sized and rated.
It is an essential component of your model.
As in real life - such as in your house - fuse as near the supply as you can.
In a model boat that's the battery.
Therefore, if you fuse nearest the battery, anything after the fuse, no matter what, can only draw up to the maximum rated current of the fuse, or else it will pop.
There's no harm in adding additional fuses wherever, depending on your setup.
i.e. if you have 2 motors fed from 2 ESC, use 2 fuses, 1 in each leg from battery to ESC.
So, it would also be wise to individually fuse any installed devices, eg., bow thruster, sound/ smoke unit, etc.,
Or wherever you drop cable size, as in lighting.
Again as per real life.
Needless to say, all cabling and connections must be able to carry the normal running currents easily.
Unfortunately, in models, getting the fusing parameters correct is not so simple as in mains supply equipment.