How do you keep track of time during a live talk?

Every time I give a conference talk, the same thing happens: I look at the clock, realize I've spent way too long on one section, and start rushing through the rest. Teleprompters kill live delivery, and plain timers only show total time.

I've been building a small tool for myself that splits a talk into timed sections and advances them automatically, with a vibration cue on every transition. Launching it here soon.

Curious how others handle this — do you use a timer app, printed notes, slide notes, or just wing it?