If you get the samarium cobalt or especially the neodymium (rare earth type super magnets) it may be less likely that the magnet will fall or be knocked off the outside of the case than a regular magnet being dislodged inside the case and go through a ring and pinion or spider gears.
Any place there are ferromagnetic wear particles circulating in a fluid it is a good idea to collect them with a magnet.
A good magnet will stick a sardine can or a Vienna sausage can (not the aluminum ones) or whatever steel can (I like Dinty Moore stew cans as they are short and wide for convennience) to a ferromagnetic surface and will then hold any small parts securely for you during a R&R exercise (if the parts are ferromagnetic.) HF sells the equivalent for several $ each.
Magnets will hold a note secure against wind or accidental loss. In the old days of steel dashes, a magnet on the dash would hold mail so it didn't blow out the open window of a vehicle with no A/C.
Parts washers can certainly be improved with a powerful magnet to collect magnetic debris. If you first wrap the magnet in tape, you can unwrap it to dispose of the metal debris. Sometimes I would wrap a very very powerful magnet in a piece of an old plastic shopping bag and use the powerful magnet to clean lesser magnets. You can subsequently clean the super magnet by removing the plastic.
If you get a pretty good magnet collection you can attach a row of them to a small angle iron or whatever and put a handle on it and use it like a rake on the surface of the ground or gravel or ... and it will find and pickup screws, nails, and such before you pick them up with your tires. I sometimes work outside in a graveled area and if I drop a nut or washer or whatever I can save lots of time and frustration finding it with a magnet rather than just looking for it.
If you have a job where you are using several screws, staples, or other fasteners, you can drop a strong magnet in your pocket and put the parts on it on the outside of your pocket. It will hold the parts securely in plain sight and you don't have to grope around in your pocket trying to find the 3/4 inch 1/4 20 Phillips and keep ending up with the 5/8 inch 1/4 28 star drive. If you drop another magnet in a different pocket it can hold a couple driver tips for different fasteners where they are easy to grab.
If you wear a shop apron or a tool belt you are probably some frustrated some of the time trying to get a steel tape measure into the provided holder. The clip is often very difficult to latch on the holder and if not latched it falls out which is not fun if you are up a ladder, scaffold or on a roof.
A powerful but small magnet affixed to the side of the tape measure pocket will hold onto the tape without your needing to use the clip and it is much easier to insert and remove if you don't have to fuss with the clip. Ditto for some other tools.
Stroking a screw driver across a powerful magnet will magnetize it so it will help hold screws onto the tip. I have placed a small magnet onto the shank of the screw driver to make the tool even more magnetic to more securely hold fasteners for me.
Sometimes people use bubble gum, grease, masking tape, or whatever to try to get a nut to stay in an end wrench. Putting a magnet on the wrench will make the wrench a fair magnet till the real magnet is removed. Meanwhile it can help hold the nut in place in the jaws. Sometimes you just don't want grease, bubble gum or whatever in "the works."
You are only limited by your imagination and ingenuity as to the uses for magnets.
I'd bet if we wanted to we could go on about the uses of magnets and exceed the number of will it fly posts.
Pat
