It is rather easy to Mystery Shop Full time when your are retired and have other income. After 8 years of mystery shopping the answer to the question,"can YOU maintain your lifestyle working ONLY mystery shopping assignments?" It is impossible to answer
So much goes into the material and circumstances you have to work with. You can have a perfectly good income for your lifestyle if you are a college student or senior who lives on Ramen noodles and Mac and cheese and are subsidized by social survival, I mean social security payments or a full scholarship.
I myself have fantasized about doing hotel shops and cruises end to end but that would involve all the rocks in the brook you are trying to cross without getting your feet wet to be there. When I do Routes they are carefully created but I get my feet wet hopping from rock to rock The total trip minus one or two segments Still makes the effort profitable. I have never been able to create back to back routes in 8 years..
Mystery shopping requires you to perform. When you stop because of illness or fatigue your business stops. . The only thing you can be full time is an entrepreneur. or investor..Whey you stop your managers or investments perform for you.