Well with film you need to think a bit differently.

Double exposure is only important if you want two sets of content.

Adding more exposure adds more shadow detail, extends the range down. This is known as placing the shadows and relates directly to choosing exposure.

The upper limit is a function of the film and/or development you choose. With negative films the scene brightness range you can get on film is naturally quite long, some films considerably longer than others.

Even with normal exposure the scene brightness range on the negative may, and in fact probably, already be considerably longer than a strait print can show. To get at that info in the analogue world we do things like burn and dodge in an enlarger to get it onto the paper.

The paper and screens are the limiting factors much more than the film. Paper and screens have short brightness ranges.

Scans can get that info too and and PS type programs can be used to get that info into the printable range. Discussing those techniques here though is off topic.