Excellent Point. By the time B-52s reach their targets nothing would be left of Russia and there would be not too many operational air bases funtioning in the United States.
Some Russian SLBMs would strike civilian airport runways that are at least 7000 Ft long. This is the minimum length required by B-52s; there were 210 such runways in the U.S. in 1977. During a crisis, big bombers would be dispersed to many of these long runways, and enemy SLBMs would be likely to target and hit these runways in an effort to destroy the maximum number of bombers. I have a plan to bring back any surviving bombers who managed to complete their objectives home but its only a plan.
A big problem with bombers, that most of them are located near ICBM bases.Making them susceptible to be destroyed in a sneak attack. That is why they are dispersed in civilian airports in emergencies.
Some decades ago I was having an argument with guy over whether the Soviet "Backfire" should be considered a viable strategic bomber against the US. His argument was that the bomber couldn't carry enough fuel for a round trip.
My response was that they wouldn't expect a base to return to. They would hit their target, head for some wilderness area, set the autopilot, and have the crew bail out. They could go camping for a while until a winner was announced. (Or have some local communist meet them and bring them to a safe house).