Depending. It seems in my experience that if you’re home more than you’re out, AND you have an inverter system, AND the temperatures are what we in Australia would consider somewhat extreme, leaving the units on seems to give better results than playing catch-up. I’ve proven to my satisfaction (using AGL’s web based smart bill thing) that even when I left an inverter system on 24/7 in a not so well insulated house, it was fractionally cheaper than turning the unit off and on. (We’re both retired and so we spend significant amounts of time at home, but this would also apply to home offices and businesses I guess.)
Interestingly, by far the biggest chunk of energy usage we had was the electric hot water system, which is set to use off-peak power. Fully a quarter and sometimes up to a third of the daily energy bill occurred during the period when the HWS was on. And on non-timed system where the tank was outdoors with no other mitigating insulation, I was able to observe that to come on for up to eight times a day in winter for fairly long periods even when I was using no hot water at all, so old HWSs would seem to be a worse issue. I imagine that using a well-insulated heat pumped HWS would reduce bills more than mucking around with whether to have the AC on all day or only when home…
It seems to me that just having access to better information about one’s energy usage is an eye-opener in that you can then see these things for yourself and make adjustments.