The decorations I bought have several modes. One press of the button turns on the lights for 6 hours, then off for 18. Repeat. They have been working for 2 weeks on very small batteries. A 50 light string, timer and battery for $2.99.
In a similar vein, I bought some LED headlights for my golf cart. I was looking over the driving/fog light selections in Autozone and noticed the boxes have a “TRY ME” button. Not really thinking, i pushed the button while looking at the light. Wow! Full brightness from just a little disc battery. And the battery and switch ( a real push button switch with knob, not just a couple of metal strips) are cheap enough to toss.
Dennis