This right here is what i fooking love about kano.is
Now my s9 is on 247 and my 741 plus small miners r on every ither day for 10h to bump up my hashing power
If you are always ramping up and down, you aren't expected to earn less than the time you are mining.
The only factor there is pool luck, which of course over the longer term is expected to approach 100% from above or below.
For those of you who might be wondering why anyone would do this, many power companies have higher daytime rates ($0.15 and more) and super low night rates (less than a nickel). It averages out to be around the $0.10 to $0.12 that many US customers pay. Having a system to power the miners off during the day and on at night dramatically increases the ROI. The main issue is that it takes longer to pay off your fixed costs (miners, facilities, etc) and difficulty continues to grow.
But if it's an equal 12 hour cycle (and most likely not), you're losing the "ramp" each time you start the miners back up the next day. Wouldn't be the smartest thing to do IMO, but if you're short on cash, you're short on cash.