This is a pretty good practice, and one that I think could be used to make a case for getting one's own office with a door, voicemail, etc. -- anything in order to create the kind of quiet zone required to get work done.
I read a study back in the early 1990's that found that the number one predictor of software programmer productivity was the size of their office, which wasn't the true cause... it turned out that the larger the office, the more likely they were to have a door. Having a door meant that they could do the deep thinking required to program well. In other words, they could lock out their interruptions.
I think most companies are still giving the bigger offices to the non-programmers, however!!

I think having hard evidence is critical when one needs to convince one's boss that "I can't work on your latest brain-fart right now..."

For the past few months I've pretty much been following the
getting sh-t done organization scheme. However, I have many days where I simply do not check a single item off my list. Why? Interruptions. It could be big things on fire which do require me to be interrupted like down servers or borked routers. Or it could be someone who works for me getting stuck and needing help. Or my boss or another manager pulling me into some unplanned situation for help. And the normal uninvited guests stopping by my desk asking for help or whatever.
What I've started doing is keeping a pad of those small yellow post-its handy. Whenever I'm interrupted I grab one and write the time down. When things settle back down where I can start working on my normally scheduled day I write the end time down and a short note on what happened. This gets stuck in my GSD notebook on today's page.
At the end of the week or whenever I'm doing a weekly review I tally up by day time lost to interruptions. (Today for example is running near 3 hours)
It has been helpful in that I've been able to use this evidence to schedule some "co-working" days over the next few weeks to get a big project over a hump. I'll be in a corner of a local coffee shop coding a way those days.