(1) Time of day effects can be taken care of in a simple manner with a (logically) simple time-of-day meter. During the 'rush hours', charges can be higher, as on some subway systems. Of course, if one wants to split hairs by having a continuous consumer-level auction, then dials and bleepers and lights and mindless complexity are probably needed - but

(2) I see little harm in some, or even considerable, imprecision, for the sake of simplicity, in time of day billing, because electricity has become a life-support system, a highly inappropriate place for the goal of a continuous auction, which is merely to save a few pennies by time-shifting. Anything that tends to require moderate overcapacity in generators, transformers, transmission lines, etc., will save lives by improving robustness. Reliable service at peak times will have but little effect on total consumption, and total consumption is not best addressed by killing people randomly on the coldest or hottest day of the year anyhow. And neither shiftless power-hungry NIMBY-obsessed politicians, nor quarterly-statement-driven business people, nor feckless consumers, will invest in robustness on their own - but when they are caught out, feckless consumers (or their heirs) will waste not a microsecond in filing huge lawsuits paid for by all.

BTW Kill-a-Watt type devices have become fairly cheap and are useful in learning the effects of specific (and not hard-wired) appliances, which may be obscured when they are aggregated on the main meter. IIRC somebody on Drumbeat may even have mentioned lending those out at public libraries.