We're great at tracking costs, money, time spent.

But where do we keep track of time saved? What bank can you put it in?

Of course you can't. You can really only spend time - so you save time in the same sense that you save $2,000 when you buy a car. You save it by spending $30,000 or $40,000 or $50,000 instead of slightly more than that. Which is really just a smaller outflow than it is a true saving.

It would be great to have a system that told us how much time all our previous efforts have saved us on a current task. With money there can be a net accumulation of 'savings' (like the car example) into actual savings in a bank.

Time affords us no such option. The only way to keep track of such savings would be to create a record of such transactions and do the bookkeeping necessary to maintain that. Something like this:

By planning ahead and due to all my previous experience, I saved an 5 hours today.

It would be great if you could show how much time your efforts saved yourself and others. Would it be worth it to keep track of those things?

A quick Google search indicates that no such record keeping system exists.