Well, you can use the new switch to switch something on and off again. Many 100 times. Per minute...
So this is my point: That makes no sense. Power switches are not meant to switch on and off in microseconds, 30 times per second for Factorio.
No, they are meant to be switched for - let's say - in AVERAGE every 60 seconds. 30 seconds on, then 30 seconds of. Again: In average!
So let's say we do it like so: We switch on/off every 60 seconds during a whole game. Let's say 20 hours. That's 1200 switch-events. Let's say that is the 50% durability of a switch. Till here the switch is very reliable, when using more it has a more and more bigger chance to break.
Again: below here is canceld
Missing maintenance works a bit different than loosing health:
- You don't see it missing for the first 10-20%
- Even then it will not be auto-repaired immediately, max. every 600 seconds.
You see: Normally used this is quite uncritical and there is no deeper game-play behind it. BUT for the case, that you switch much faster, like 30 times a second, the time that is needed to break the switch (the 1200 switch events) is then only 40 seconds!
That's faster, than the automated switch maintenance might be repeated. So the switch will fail at some time.
The interesting thing is then: Nobody can know, will it fail when switched on or off (the breaking depends on a probability). That will lead to really interesting situations.
That will also lead to interesting effects in the factory. The formerly (more or less) unwatched switch is suddenly much more important. Or you cannot use the switch as a switching power supply (the power supply in/for your computer switches on/off some hundred times per second to regulate the exact amount of power). At the same time the switch has not been loosing it's usability.
And it spares us one fix: How to display a number of devices that are continuously switched on/off. See viewtopic.php?f=6&t=27436
Even if the icon is fixed and will not longer blink, it will be quite disturbing, when the player creates some kind of circuit, that switches on/off very fast.
So - if you ask what this should be used for: For the case, that a player uses a power switch as regulator (need to switch on/off several times per second), Factorio does normally not forbid strange usages of entities/items, but in this case it is a bit of graphical glitch. And it really doesn't forbid it, but you need take care about it (place an inserter, which fills in repair packs into the switch?!).
As always: The exact numbers are balancing...