Scale at 100% or else?

Melissa is saying in a support mail:
"When setting your scaling percentage to anything lower than 100%, you could run the risk of not participating in system trades because we cannot trade in fractional units."
Say there is a system that 90% of the time trades 1 contract, does that mean that scaling at 50% means no contracts will be placed?
My interpretation of scaling was when multiple contracts are placed then the scaling kicks in.
i.e If the system trades 2 contracts, scaling at 50% means 1 contract is placed, right?
In fact the scaling widget in the control panel shows that as well.

please clarify, ta