Of course, if you run your gear 24/7 in "awake" mode, you may be presented with the opposite problem, where your SMPS "start up" circuit has failed.
Only when you have a mains failure, do you notice this.------great fun being stuck with several devices which won't turn back on.
Even more off topic, but a good story, so being an O.F., I will tell you anyway:-
Back in the day, I was tasked to lead a team automating a TV Transmitter site which used Tx which had never been designed for such service.
With a lot of workarounds, cut & try, etc, we got together a system which was effectively "a Tech in a box", using a Programmable Logic Controller & a whole raft of electromechanical interfaces.
This, when it received the right signal from the Studio (the presence or absense of vertical syncs) would, in turn, switch on the tube filaments, wait 5 minutes, then apply the HT.
At closedown, it would perform the opposite procedure.(it also did a lot of other stuff)
All good, but if there was a power loss, then the emergency power plant (EPP) took over, we needed to "truncate" the procedure to get back on air as quickly as possible.
To do this, we needed an input to the PLC to indicate the loss of power.(It could detect this itself, but didn't provide it as an input).
This site used -24v fed aound the building to do various things, & this was normally provided by a Mains operated power supply.
In a power failure, the 24 volt EPP starting battery would take over via some "steering diodes".
We blithely connected our PLC input to the "unprotected" side of the diodes, so that Mains loss should cause the loss of -24v, & trigger the fast TX restart
Several "simulations" of a Mains fail worked OK, so the system was put into service.
The first weekend, I was callef out for a transmitter failure.
I was presented with the spectacle of both sound transmitters up ok, but both vision Tx with HT on & no filaments.( needless to say, this is an undesirable condition).
It turned put that the large electrolytics on the supply kept the DC voltage applied to the PLC input up long enough for the normal startup procedure to occur, but without the initial "fils on" step.
This was quickly "bodged up" by bulding an unfiltered DC supply in a handy plastic box, plugging it into the nearest power point with a "don't turn off!" sign attached, pending the provision of a better alternative.
The only relevance this has to the thread is that it is incredibly easy to set up a system where the unintended consequences are so weird, that they are overlooked.
We assumed that the worst case result of this input not working being the controller just reverting to its normal start up sequence, rather than what actually happened.
All the other functions worked perfectly.