1. You can only use class II equipment with pre-1966 lighting installations without an earth, but this will not cause bulbs to fail.
2. LED bulbs can be affected with spikes on the supply, having a surge protection device (SPD) will likely reduce bulb failures.
3. Bulb price does not relate to bulb quality, so expensive bulbs will not help.
4. Any switch of bad connection can cause spikes, so
@sparkwright comment on poor connections is good.
5. Often dimming switches can either produce spikes or remove spikes, as with any electronic switch.
I have moved to LED in both last house and this house for most of my lights, and can count the failures, even when going back 5 years or more since so few, I had so poundworld G5.3 0.58 watt MR16 lamps fail, they were really toys, I had a 5 foot replacement for a fluorescent fitting fail, rather annoying as not cheap, and a G9 bulb failed, and I decided to set what was inside it, found a dry joint which I corrected, and it is now working again.
I would guess around 35 LED bulbs in this house, may be more, been in this house around 2 years, the houses before also used LED and no fails other than listed above, so the big question is why do I have no problem and I use cheap bulbs, and others have problems, I can only guess, and my guess is because this house has a SPD fitted and non of the houses were near an industrial area or supplied with over head power lines from local transformer, so unlikely to have any spikes on the supply large enough to cause the LED to fail.
I have had problems with LED, but not failing these two
View attachment 241588 LED's are both G9 fitting, the large one has a smoothing capacitor inside nearly as big as the small one, so the small one flashed when switched off until a load capacitor was fitted, then shimmered when switched on, it was a well known make and complied with all regulations, and the glass cover would still fit when using the small LED. The large LED no flicker, brighter, did have one which had a dry joint it failed within a day, and repaired, they were cheap, no brand name breaks the rules by not showing wattage or lumen output, but work far better than the expensive smaller one.
I have had problems with smart switches, and have started to move to smart bulbs, to date the smart bulbs (zigbee) have been better, except for one event, I had four smart bulbs and smart switch in my bedroom, and I turned down the smart bulbs so as not to attract flying insects at night, and the wattage dropped below the minimum for the smart switch so all lights turned off, fitting non smart bulbs did not allow me to switch lights back on, and I had to switch off at consumer unit and back on again to get smart switch to work again.
But smart switches and dimmer switches do seem to stop the spikes with cause bulbs both tungsten and LED to fail, but unless one fitted an oscilloscope to the supply it would be hard to say what causes LED bulbs to fail, I in the main use Lidi, B&M bargains, and Home bargains to buy bulbs, i.e. cheap ones, the only exception was the replacement for fluorescent tube was
screwfix (and first one failed) and the G9 which do not comply due to not being marked with watts or lumen came from internet.
So I would say you have been very unlucky.
The non earth problem is some thing else, had it with parents house, and also found wired with rubber insulated cables, the rubber was well past use by date, and my father said "I am not living in a building site, you can re-wire the house when I'm gone." and that is what happened, RCD's would not hold in with the old wiring and it was clearly in a dangerous condition, so when late mother went into hospital we hired a firm to rewire the house, speed was critical as would cost around £600 a week for mothers care if not completed on time, so went with a large firm who could complete fast.
I had only a basic re-wire no extras, and kitchen had already been rewired, seem to remember cost around £2500, and I did the re-decoration plastering etc. As said very basic re-wire, I wanted it safe for mother and able to rent the house if she went into a home. So no frills.
