Workout App

When I need multiple functions, like a timer when working out, I just use more than one app. Search the App Store for an app that provides the thing sequence you need. Be sure the app you select supports the  Watch.

Follow these steps if you want to send feedback to Apple:

• Open your web browser of choice and enter www.apple.com/feedback into the URL or Smart Search Field. ... 
• Select your Apple product from all the ones displayed on the screen.
• Fill out the Name, Email Address and Subject fields.

Use Apple HIIT

High intensity interval training (HIIT)

Choose HIIT for cycles of intense exercise, followed by shorter periods of rest or recovery. For example, you might jump rope for 45 seconds, rest for 30 seconds, then repeat. 

Some of the irregular movements in HIIT workouts might prevent a heart rate measurement. If heart rate isn't available, calories are still tracked using the built-in accelerometer. If you're not able to get a consistent heart rate during HIIT workouts, you can connect your Apple Watch to a Bluetooth chest strap.

Search especially for "HIIT Timers"

I'd forgotten about that. Good catch.