How often should you have your parking lot swept?
Parking lot sweeping is regular maintenance.  Many variables need to be considered when deciding this.  A few things to consider are how much and what kind of debris accumulates in your parking lot.  Locations like bars, restaurants, and shopping facilities require more frequency because of the amount of traffic that leaves trash like cigarette butts and empty bottles. 
Also consider Mother Nature.  Is your parking lot near open fields where dirt and sand are being blown onto the lot?  Are there a lot of trees and shrubs dropping leaves?
There are many variables to take into account. We would be pleased to assist you in the decision-making process.