1. Clock-only triggers. A routine that fires at a fixed time ignores whether anyone's actually home. It works for a week, then quietly starts turning on lights in an empty house until someone notices and disables it.
2. Two routines reacting to the same sensor. When a motion sensor triggers both a "welcome home" scene and a separate security alert, the two can end up toggling the same light back and forth. Give each sensor one clearly-owned routine.
3. No quiet hours. Notifications for every door open, every motion event, and every temperature change add up fast. Grouping alerts and setting quiet hours for low-priority events keeps the ones that matter from getting lost.
4. Automations that never expire. A routine built for a specific event — houseguests, a vacation, a renovation — often outlives its purpose because nobody revisits it. A quarterly five-minute review catches most of these.
5. Assuming more sensors means more "smart." Adding a fifth motion sensor to a room that already has four rarely improves anything; it just adds another device to firmware-update and another point of failure. Coordination beats density.
None of this requires new hardware — most of it is just revisiting routines that were set up once and never questioned again.