Would a huge consecutive run of say 60 UNC 1974 $2 (only worth $9 in UNC) be worth anything more?
Any premium?
Your run of consecutive notes is not the same as a block of stamps.
I have never seen premiums paid on runs of new (common) notes. In fact, the market will typically offer you less, just like when a book seller (or any other sales person) sells "batches" or a larger number of said product.
So rather than expect $30 for three- I would expect $15 - $20 for three in a row. Some people like having consecutive numbers- so they may be a bit easier to sell simply because some people (esp non-collectors) like to show off having a few rather than 1.
The exception to this rule may be for fancy numbers or rarer varieties (errors), in which case premiums may be reached.