I'd be surprised if my daily driver phone ran out of battery more than once or twice a year. It probably only ever reboots in exactly the same 24 hour time window as every other iPhone during iOS updates.

If Alice's threat model doesn't include NSA/KGB/MSS/MOSSAD, just being slightly less naive and switching on the burner at (or within a set distance from) some location other than her home is likely fine. I describe in another comment here: https://news.ycombinator.com/item?id=45009042 how I used to automate turning on a phone (well, a 3G WiFi hotspot) at a set distance from a nearby library.

But don't follow my advice if you're running a global drug cartel, or criticising Saudi Royal Families, or defending the rights of Palestinian children to not be bombed.

(I just realised my phone goes into and out of airplane mode when I get on and off planes, which narrows it down to one in a couple of hundred people for one flight, and likely uniquely identifies me with only two or perhaps 3 flights. But this is my daily driver phone with proper KYC identification, not a burner.)