There are two important things to keep in mind, however.

Firstly, several Soviet missions failed merely because autodocking of Soyuz spacecraft failed. Even when it did work, there were many issues that persisted for years.

Secondly, many Salyut 6 and 7 launches existed for no other sake then to give the incumbent station crews a new spacecraft.

At the time and even now, Soyuz spacecraft only have a limited recommended amount of time they can safely remain fueled and active before they 'retire' and must return. To overcome this, the Soviets launched fresh spacecraft with, "guest" cosmonauts who would swap seat liners and return to Earth with the old spacecraft. The Soviets in turn tended to fill these fresh Soyuz with foreign provided cosmonauts under the Interkosmos program. Rather cynically, they were not expected to do much and given little-to-no training on operating the actual spacecraft; such tasks were left solely to the Soviet cosmonauts who accompanied them.

On a related note, the Soyuz 12 and 13 "free flights" occurred in the wake of Salyut 2's failure, as the Soviets had already prepared the spacecraft for flight and would not have Salyut 3 up in orbit before they reached their sell-by-date.