Sometimes we should avoid using bitpacked encoding

[doki23]

For instance, the bit_width is 7 and the type is u8, the benefit is so small that we can return an Err to avoid encoding.

[gatesn]

Yup, completely agree. We need to introduce some concept of this into the objective function of the compressor. A sufficiently small ratio should be penalised for slowing down decompression throughput.