Indexing temp tables in stored procedures.

Is there any advantage to creating indexes on temp tables created in a SQL stored procedure?

In theory, creating an index on a table where that data element is used for joining or selection should improve performance. But so far the indexing doesn’t seem to make a significant difference. Perhaps my sample data is not large enough for the indexing to come into play.

I would be interested in opinions on this topic.

And to those who post responses, my thanks in advance for making the effort.