Adjust lights according to needs on same ride, or bright all the way?
 

Here is the issue: I don't feel like using full battery power (lights on High, or maximum number of lights turned on) when unnecessary, then only to have insufficient battery power left when I'm on the darkest and final part of my ride.

So suppose you start the ride in late afternoon or at dusk, gradually you'll need to turn on more lights on the bike, then maybe when you are returning at the end of the trip it's pitch dark, or the road is most dangerous, so that's when lights are most important for you. Do you, to begin with, turn on minimum light first, then as it gets darker (or traffic area gets more dangerou), you get off the bike, and turn more lights (most don't have remote control of taillights) on, then continue riding? Or do you forgo the hassle and simply turn all the necessary lights on and don't care if later the lights will be weaker due to low battery power?
(Emphasis: it's not just about cost: you want to have optimal battery power in the most dangerous part of your ride, or when it's the darkest.)

(This is not an issue if you start in the most dangerous/darkest part, then gradually lights become less necessary.)

(Also, this may be more of concern for people who don't use high-power rechargeables which can last a long time with same brightness.)

Please share your thoughts and experiences.

I certainly adjust the mode of my lights depending on conditions. I.e. during the day I just want them to be seen, so I'll either have them off in areas with little traffic, or in bright flash mode in areas with more traffic risk. At night I still opt for the bright flash mode in areas with sufficient lighting but lots of traffic, but switch to bright-steady in areas with less lighting. And I'll switch to dim-steady on MUPs.

The battery life on my lights is sufficient that I rarely have to worry about it. But if I were doing a very long ride at night then I'd use the dimmer light setting in areas with less traffic and other light distractions (I find that relatively little light is needed in really dark areas where my eyes become dark-adapted).