As an electronic engineer with over 30 years design experience I have used many different types of LED’s in various applications and this is one of the most absurd things I have ever heard of.
There are many reasons why LED’s die but I can assure you pulsing them within their specs is not one of them.

If I get time later today I’m going to have a look at this lamp check signal on my own vehicle with a CRO to see if there’s anything unusual with it.
If it’s a simple 0-12V switched signal, then there is no possible way this would cause premature failures.
If the signal switches from positive to negative there is a possibility this may cause issues if the lamp unit is not designed correctly as it would be momentarily applying reverse polarity voltage to the LED’s which they don’t like. If this is the case, the cause is a design issue with the lamp unit and not the fact that the LED’s are being pulsed.

As an example of pulsed LED’s in an automotive environment; have a look at the brake/tail lights of any high end Audi or VW with LED lights. You will notice there is a bunch of LED’s that are used for both the tail and brake lights. These are pulsed very quickly to reduce their brightness when the tail lights are on without the brake lights, the pulsing stops when the brake lights are on to provide the added brightness for the brake lights. You will probably also find this setup on other Euro cars and from memory the later version of the Prius is setup like this too.

I'm sorry but you are going off on a tangent and are completely on the wrong subject. I am not going to continue this debate with you as you are obviously convinced you know everything, and i am not willing to continue accepting your rudeness. I do not make absurd statements. You apparently know nothing about BMWs, or cold monitoring of LED Angel lights. End of story!!

Cold monitoring off for Angel Eyes - KALTUEBERWACHUNG_SL_LV-nicht-activ; KALTUEBERWACHUNG_SL_RV-nicht-activ

Angel eyes still work when turned on but no longer flicker when engine first started.

Unfortunately I do not have the equipment to do this myself, so I Try to remember to turn mine on before starting engine to prevent cold monitoring from occurring

Thanks Frozenwaffles for your replies.

I have checked both the cold and hot monitoring lamp check signals on my own X5, with some interesting results.
For the benefit of those non-believers on this forum I performed this test on the angle eyes circuit, although the results are likely to be the same for a number of other light circuits.

During hot monitoring the bulbs are pulsed once every 80mSec with a clean ‘square wave’ from 12V to zero and back to 12V, this pulse is about 5mSec in duration. The hot monitoring phase starts more or less straight after the cold monitoring phase and is done so that if a bulb fails while you’re out driving around it will bring up a warning on the dash.

During the cold monitoring phase I found both positive and negative pulses.
While the positive going pulses should not cause any issues, the negative going ones are large enough to potentially damage a LED.
As I have mentioned previously, the issue is NOT the fact that the LED’s are pulsed, it is the fact that during the cold monitoring lamp check there are negative pulses generated which LED’s are sensitive to.

A simple solution for those who don’t have the ability to turn this off would be to splice a diode of suitable amperage (eg IN5401 or similar) in series with the angle eye circuit with the grey wire connected to the anode and the cathode connected to the positive side of the LED.