Before signaling on a subgraph, it is important to take a subgraphs total signal into account. Doing so will help you to understand if you are one of the first Curators to curate the subgraph or if you are already late to the show. Based on this, you will quickly see if it makes sense to signal your GRT or not. Keep in mind that your risk analysis should take the expected reward into account while weighing in the risk of signaling the subgraph with its present signal.
A subgraph may be highly attractive but if the total signal is already relatively high, you are exposing yourself to a high risk. If your assessment is correct, however, other Curators will come to the same conclusion and the subgraph will generate a high volume of queries, which increases the value of your curation shares.
Ideally, you are able to discover the subgraphs that are undersignaled but of high quality. One reason these subgraphs are undersignaled could be that they are not yet generating query fees as the project has not yet started querying the subgraph from its dApp.