Electricians - Are you charging time & material or flat rate right now—and why?

Curious what’s actually working for everyone in today’s market with rising material costs and labor rates. 

Currently - I do time + material and then add in my overhead/profit % and I still get tons of kick back. Other big electricians in my area charge 3-4x the amount for something that I do and it works for them. I can't wrap my head around it.