On Cessnas we leave the beacon on at all times for two reasons:
- When the engine is running, there’s at least one warning light for people outside the plane
- When the engine is no longer running and [you think] you’re done wrapping up your flight it’s a sign that at least the BAT Master switch is still on when you see the Beacon still flashing (which will hopefully be a good reminder to use the checklist at the end of the flight as well!)
On the Twin Stars we use the strobes for the same purpose as there is no beacon light.
Just a couple of days ago someone managed to leave the electric master switch on upon leaving, draining the battery and causing the plane to be temporarily inoperative for everyone else – MX needed to jump in and fix the problem for the next pilot, causing both hassle and costs.
Had the strobes been left on it would have been very hard to overlook the issue (although that is still no excuse for not using the Shutdown checklist).
So please – use the checklist properly at all times, and follow the beacon / strobes policy.