When I first started in this business in the 1950's, most decent size cities had their first runs theatres (often with several hundred to a thousand seats) downtown. A picture would open for one week (two if it was a really long run) and then roll out on an established pattern. Usually four weeks after opening the second tier (usually large neighborhood theatres) got the picture, then finally about four weeks after that came the grind or nabe runs.
With the exception of certain roadshows. the six to eight week first run engagements did not really begin until the late sixties comming somewhat conincedentally with the rise of the shopping center theatres.
Now with the gigaplex and the same picture on multiple screens (thereby acheiving the thousand seats of the old downtown palaces) we are back to where we were in the 50's - burning a picture out in one to two weeks.
Everything comes full circle.