I think the only way to check on this would be to note what classes you have dedicated indexes for, then for the Work index, you could go to the class "Log-Cluster-FTSIndex" and open the latest entry for the Work index. In this it will have a property that shows what classes were chosen to be indexed or it will say something like "All-Classes".
What I was trying to establish is whether we were indexing more classes than we actually need and therefore increasing the size of the search index unnecessarily.
For example, if we'd initially used "All Classes" and then later decided we only need a few for example. I've probably want to re-do the index just for the work classes we are using if you see what I mean.