Help with home assistant multi switch automation

I am somewhat new to home assistant and looking for recommendations with an automation. I have an automation to set multiple lights to 50% brightness and I notice two things:

  1. Sometimes there is a delay or timing issue where the lights turn on at different times. Is there a way to make it more reliable that they all turn on at the same time?

  2. I have noticed some lights get stuck with bad flickering when using my automation. Do I need to be adding in delay or a ramp up in the automation? Turning the lights on at the switch and changing brightness never causes the flickering. Light bulbs are Philips ultra definition LEDs.

Thanks for the help,
Tim