How long does it take a doc to fill up seven cavities?

Depends: Depends on many things. The type of cavities, size of cavities, location of cavities. Also the type of filling material which the dentist uses for the restoration. Dentists work at their own pace. Some work in microscopic surgical loupes which can help them see decay that they might have missed with the unaided eye & it can take more time. The patient can also be a factor.

One to two visits: Depending on the extent of each cavity. Generaly we treatment plan patiens for quadrant dentistry.That is we divide the oral cavity in 4 sections and work a minimum of one section per visit. However local small cavities that do not require local anesthesia can allow for additional restorations. It all depends on your doctors ability, your tolerance , location of cavities and time involved.