This is basically the design of UTF-8 or varint encoding. The integer's representation is read one byte (8 bits) at a time, which can then be interpreted by looking at the first bit which says whether the integer is "done" or more bytes need to be read.

(If we were using all 8 bits for the representation and an additional leading bit for whether it continues, we'd end up having to read 9 bits or something, which is awkward and not aligned with what the machine actually supports reading.)