تعریف و معنای "[stretch] {one's} legs according to the coverlet"

What is the origin of the idiom "stretch one's legs according to the coverlet" and when to use it?

The idiom "stretch one's legs according to the blanket" likely originates from a traditional concept of being careful with using one's resources. The phrase alludes to the idea of making sure one's legs (and thus oneself) stay comfortably within the boundaries set by the size of the blanket or coverlet.