I think running at 10% is not safe for the most of the users who don't have at least air-condition on in their room because your PC/laptop can easily heat up high at normal room temperature and if you run at that high temp then it is not safe for your PC.
What on earth could make anyone think that? I repeat again they will quite happily run at 100% unless there is something abnormal to cause overheating. By abnormal I mean it would require that a) The airflow is blocked in some way like the heatsink being clogged with dusk or the computer air inlets are blocked and b) The sensors that monitor the CPU temperature for protection systems are faulty.
You could run a CPU at 100% 24/7 and it will still be running many years after it has been made obsolete by several new generations of chips.
Again if you reduce to 20 or 30% then your earning will be the very negligible amount.
This is designed to be used by someone who is already claiming from the faucet and add a few extra satoshis to their account. It does exactly what it is supposed to do.