On the site, in some cases, for the same version of a piece there is the Full Bass Score and one or more extracts (the Solo or the Bass Line, for example). Why?

When listening to a track, first the interesting material to work on for the transcription is identified, such as the bass solo. Later it may be decided to complete the transcription and this constitutes a separate new article. The opposite is not true: if a Full Bass Score is released, no extracted portions of it are proposed as independent purchasable items since, if so, for each complete transcription there would be 2 or 3 additional items each time and this would be redundant.