Yes, shelf life is an issue with Xenon strobe based lights. There is a flash capacitor in the strobe driver module that needs to be excercised (charged up) on a regular basis. If it sits too long (months) without being charged up the electrolyte relaxes and the capacitor can fail prematurely if it isn't reconditioned properly. Abruptly charging it in normal use after it has sat too long without first reconditioning it (applying a gentle charge-up) can damage them.
The shelf life after leaving the factory is about 24 months. If left unused for 24 months after active use, the same applies. The official way to recondition for use, the capacitor is as follows:
Hook the strobe power supply up to a variable (User selectable) voltage (output) power supply that is rated (amps) for the current requirements of the strobe power supply. If don't have this available most avionics shops or electronics repair shops will have this capability.
(this is for 12/14 VDC units only) I do not have this same info for 24/28 VDC strobe supplies. With
NOTHING attached to the Strobe Power Supply output (no strobes attached) do the following:
Power for 15 minutes 3 VDC input,
15 minutes 6 VDC input,
15 minutes 9 VDC input,
15 minutes 12 VDC input
The unit is now ready for normal installed use with strobe tubes attached.
My Whelen strobe power supply sat unused (during construction) for 19 years, (Yes, it took me that long with a 10 year hiatus in the middle, long story)
Used this "program" from Whelen and the unit has worked perfectly for about 200 hours so far.
As a proactive precaution, I would follow this proceedure with only 1 year of non use, It will not hurt the unit and is a proactive effort to protect your investment.