It's impossible to answer a generic question about MSC policies because each are unique companies. There isn't really a set of standards applied to all. It is reasonable the same person would use the same parking garage on a regular basis. Same with shopping at the same grocery or convenience store weekly.
Rather than relying on the MSC to cut you off, use your best judgement to evaluate if your actions are giving you away then create your own rotations. By doing so you are protecting your mystery shopping business.
Equal rights for others does not mean fewer rights for you. It's not pie.
"I prefer someone who burns the flag and then wraps themselves up in the Constitution over someone who burns the Constitution and then wraps themselves up in the flag." -Molly Ivins
Never try to teach a pig to sing. It's a waste of your time and it really annoys the pig.