Unfortunately, one of my 4 super-high-brightness LED bulbs I am using is already failing (it is flickering). I have a spare and it is covered under warranty, but I haven't had the time/energy/motivation to swap it out yet (since it is a front bulb, which is a PITA). Otherwise, I love the bulbs I bought (first TRULY bright bulbs I have seen, and excellent light distribution and color).
Well, over the years I have had multiple front 1156PY (BAU15S/PY21W/7507) LED bulb failures. The problem is most likely heat. Although such bulbs typically pull only 5W, they all seem to be designed as turn signal bulbs- meaning they will only be used for a short time, and then only "on" about half the time (due to blinking). My mod (which is EXCELLENT for safety) has the bulbs on all the time as running lights, blinking OFF when used as turn signals. So the heat builds up in the tiny space and ends up damaging something- perhaps the LED's themselves, but it seems more likely the regulator inside them that steps the voltage down.
The results in a bulb that works great for a year or something, then random occasional flickering of one or more of the LED elements. In subsequent months, this will get worse and result in more and more flickering and/or some segments going permanently dim or just off completely.
Even with years of advancement, and tons of searching, it seems nothing has changed much in the bulb designs. Some now even say on them "not to be used as running lights", clearly admitting they cannot tolerate being lit all the time. Those bulbs that do have reasonable heat management seem to only be those with built-in load resistors, which defeats the whole point. Those will intentionally suck 20+ watts to be compatible with systems that don't already have an external load resistor or upgraded, electronic turn signal controller/relay.
So it looks like I am resigned to just having to replace them every year or two. Still worth it for the safety. I have no other bulbs right now, and both the front ones are freaking out, so in a few hours, I will be swapping the fronts to the rears (the rears are the same model, but are rarely "on", so they should work OK up front for a while). And the front ones have enough light for just blinking on the rear, plus I have the Admore bar with additional turn signal indication in the rear. Then I will just order some bulbs on Amazon for spares based on looks, since nobody will have any data about using them as running lights. JDM Astar doesn't seem to make non-load-resistor LED 1156PY anymore.