FrankT said:

Interesting. Seems an awful waste, but I get what you're saying.

Well, it's just how things evolved while trying to keep everything compatible.

Nowadays, films don't need to be shot like this since everything is scanned and put into a computer. Filmmakers can shoot using a 3-perf pulldown, which gives them a large, native 1.85 aspect ratio AND 25% film savings. Some can also use 2-perf pulldown for a near 2.35 aspect ratio and 50% film savings. Here's a visual:

Recently, some have shot films using 1.3x anamorphic lenses on Super35mm film (example A from above) giving them the entire 4-perf film area, but with a wide 1.78 aspect ratio.