The following stories each focus more closely on a single location. Thus, in the original Time Patrol tetralogy:
Everard travels from his apartment to Persia 542 BC to rescue Keith Denison;
Everard and John Sandoval travel from Everard's apartment to North America 1280 AD to prevent a Mongol invasion;
Everard and Piet Van Sarawak travel from the Patrol's Pleistocene Pyrenees lodge to an alternative 1960, back to the lodge, then to the Academy, then to the Battle of Ticinus to prevent Carthaginian victory in the Second Punic War. (Ticinus is the only historical location in this story.)
I could proceed through the series. Readers who are already familiar with it will know that it becomes more complicated. In "Star Of The Sea," Everard and Janne Floris follow the life of a pagan prophetess back through time until they themselves unintentionally trigger the event that makes her a potentially history-changing prophetess worthy of their investigation.
Can any subsequent sf writer possibly surpass Time Patrol and The Shield Of Time as a time travel series?