The syllabic l is confined in practice to forms built on a single Sanskrit verbal root, the one meaning to arrange or to be fit, and to the derivatives that root produces. That is the whole of its working range in the classical language. The grammarians nevertheless give it a place among the vowels equal to that of a or i, because they class r and l together as the two liquids and the analysis requires that the syllabic form of each be treated the same way. The result is a letter in ninth place in the order that a text may run for many pages without needing.
The pairing of the two liquids is not arbitrary. The rules of junction treat them as a matched set, the strengthening ladder applies to both, and the four letters for the short and long forms of each stand together in the order to show the correspondence. A learner who has the pattern for the r vowels can predict the behaviour of the l vowels without being told, which is exactly the economy the table is built for. That the second pair has almost no words behind it is a cost the tradition accepted knowingly, and the classical grammarians say as much rather than pretending otherwise.
There is a further consequence for a reader. Because the letter appears in so narrow a range of forms, meeting it in a text is a strong signal about what word is being read, in the way that a rare letter in any writing system narrows the possibilities quickly. An epigraphist working on a damaged surface can sometimes use it that way, reconstructing a word from a single legible sign because so few words could contain it. A rare letter carries more information per occurrence than a common one, which is a small compensation for how seldom it turns up.