So there should be no doubt about that. The question is which devices should u use. So for that desktops seem to be the only choice. Don't mine on smartphone, tabs or even laptops, even if you have free electricity and all. You will eventually burn these devices!!
Most devices use thermal throttle on the CPU. That means it reduces CPU power if this one becomes too hot, in order to protect hardware from burning. If you feel your device is too hot (for example if you use it at the same time it mines) then reduce CPU usage.
I've already deposited as low as 1000 satoshi on my freebitco.in account.