I have run across a number of cabinets with loose lid or leaf hinge screws. Those that hold the machines in place seem to be especially prone to coming loose.
On some of the Singer cabinets they have flanged threaded metal inserts that come up from the bottom of the cabinet top so the screws thread into them for the machine hinges. For any cabinet used a lot those would great for a retro fit. I've seen them at hardware stores.
For the others I've found that occasionally checking and tightening the screws goes a long way towards preventing them from stripping out or coming loose.
For those that have already stripped to the point they wont stay tight, I take either a rolled up piece of veneer scrap or some other scraps and push them into the screw hole with some wood glue. I do this to all the holes, then reassemble the hinged part and tighten the screws up. When I've done this none of them have come loose again.
This works great for cabinets with drooping lids.
When I use my machines often I leave the heads up, and either put the leaf up and over the top of the machine with a pad between the leaf and machine, or I use a cover and just leave it set up.
I know space is a premium, but I just make room for my machine.
Joe