Yes because many times my employers focus on chasing the next customer/corporate initiative so trying to do things quick/dirty without thinking of ways to make things easier. So you have one hack on top of another hack (granted I'm sure this does not apply to Google) and there is a cost in maintenance but the employer refuses to acknowledge technical debt....
So using the 20% of time you can go after technical debt, automating annoying processes, etc... Many times you have a manual process and it is way quicker to do it than to automate it, but it does distract, and take a toll on morale because repeating the same thing is boring, and as a developer it is annoying and probably will have you seeking other employment if it gets annoying enough. This way you can automate those manual steps even though it may take a long time to pay for itself.
One example from a prior job:
Instead of chasing around e-mails for auditors, just set up a quick e-mail bot that can parse change request forms and the correspondence behind them (e.g. just CC the e-mail bot). Then when it is time for the audit, either send the bot a message to get the entire issue in a zip file with all correspondence, or retrieve via a web interface.... Ultimately it will take longer than manually hunting for e-mails. But over time considering the number of people involved this will probably pay for itself in a few years....
Another example:
They had a hosted application and the database was too big to restore locally. They were creating DTS packages against the database (quite challenging to do without a copy of the database), sending it remotely and having technical support at the hosted application install the package. Often technical support were idiots and would install the wrong package several times, or install an older one somehow messing things up between the e-mail, their ticket system, and the DBA. Additionally the only real test of the package with full data is in the hosted environment. Still creating a DTS package is much quicker than a .NET application to manage data exports via database tables where we could control the deployment of new data feeds in the short term. I suspect in the long term it would have paid for itself within a year or two. But anyway without hard proof (and even with hard proof) there is no chance to be able to work on it. But with a 20% project it would be done, over time it would pay for itself, and future employees would be quite grateful for having such a tool instead of the old painful method with DTS packages.....