The first California deregulated electricity market had an auction every half hour and all pricing was spot. This caused blackouts and the bankruptcy of Pacific Gas and Electric, even though it was what PG&E had lobbied for.
Today, most markets (at least PJM and CAISO) have a "day ahead" auction, and a current auction to fine-tune. Most of the market is in the day-ahead auction. This seems to have reasonable stability.
I've read that the overall effect of electricity deregulation is that prices are slightly lower, and reliability is down. Rate-of-return regulation encourages utilities to overbuild somewhat, which is not necessarily a bad thing. Beats under-building.