Depends on the show. If they're old, it could be because they were made to only be watched weekly. Some shows are also too formulaic/repetitive to marathon-watch but still good in small doses. Your best bet for binging is anything with continuous stories/arcs. Alternatively, anything that has episodes that constantly end with cliffhangers can also be easier to binge watch since the urge to find out what happens is heavy.
The service you use to watch them also matters. Netflix pretty much has the lock on how to optimize streaming into the next episodes with some shows automatically skipping the intros after you see them once to make it even easier. On top of that shows made for Netflix were designed with binging in mind so they make it easier too. Hope this all helps.