This is an accepted solution.
You can choose whether the 'Apartment/Suite' line is required, optional, or not available at all in your Checkout Settings.
If you make it optional, then customers that are in a single-family home can simply leave the line blank. If you make it required, then they will have to enter something (such as N/A). If you make it hidden then the line will not be visible at checkout.
Most stores have it set as optional.