We’ve all heard the cliches: Time is valuable. Time is our most precious commodity. We’ve even seen the studies: A time-saving purchase makes people happier than a material purchase.

And yet, most people avoid actually taking the time to, well, track their time. It’s understandable: For decades, if not longer, people have been using crude, unpleasant means to keep track of what they’re doing — spreadsheets, handwritten tables, or mental notes. Filling out a timesheet at the end of each week can be arduous and unfulfilling.

But like many areas of our lives, technological improvements — mainly powered by the apps on our smartphones and other smart wearables — have made it easier to keep track of how we’re spending our time, both at the office and around-the-clock.

Whatever tool you use, whatever app you choose, whatever means you desire, if you start tracking your time (maybe you’ll begin with a spreadsheet, then move over to an app that can help you drill down or get even more accurate data) you’ll start finding out things about yourself, your workflow, and your productivity that you never would have noticed otherwise.

We spoke to seven professionals who have tracked their time for various reasons and by various means, and they shared their surprising findings. What will yours be?

(*Note: Some of these responses have been edited for clarity.)

1) Checking email is a bigger productivity killer than we think

Checking email is one of the biggest roadblocks to productivity. Looking at our email feels productive, but what else do you do for, according to some estimates, four hours a day, that yields fewer actual results?

The issue, according to Michael Roub, managing partner at Inflection 360, is that we don’t schedule email checking, and instead we allow it to take over our days.

“About a year ago I made the painful decision to start manually tracking my time for a few weeks to understand how long each task was taking,” says Roub. “I was able to confirm that I was putting plenty of hours on my desired tasks, but I quickly realized that my email use was repeatedly disrupting my day. It caused me to re-think how I planned my time.”

“I started building email review and response into my schedule at three distinct times… I continued to tinker with the amount of time allocated for emails and found that 20–30 minutes was the most I should allocate at my planned intervals,” he says.

But checking email is so easy to do — open the tab, tap the app — it seems like the disruption should be minimal, right? Wrong.

“A typical worker requires approximately 20 minutes to regain focus on their work,” after checking email, Roub says.

As a result, email doesn’t just distract us for the time it takes to open our inboxes. The ripple is felt for hours each day.

2) Multitasking is killing our productivity