Sewer scoping for Preventative Maitenance

[Alyssa Yumi Nelson]

I am curious about how often landlords perform sewer scoping as part of preventative maitenance. I can find info/advice on scoping as part of initial due diligence but not so much as a PM effort. Although my property in Baltimore isn't exhibiting any symptoms, it hasn't been scoped in at least 5 years. It's a 100 year old home, although city records state a permit was requested for water/sewer line re-construction in 2005. Main reason I'm hesitating is because I'm getting quoted $700 to get a scope done. Any thoughts?