Oh, I use flex-bits when they're the right tool. I've gotten very good at knowing what I'm hitting by feel and how far the bit moves forward after penetrating the last framing member.
Looking at upstairs plumbing fixtures and HVAC outlets can go a long way toward avoiding hitting those utilities. Keeping the tip of the bit down close to the ceiling drywall helps, too.
When adding recessed lighting in a kitchen with living space above, flex-bits are almost a necessity in order to avoid patching. They're also the best way to get wiring to a new switch.