On the Test Monitoring Overview page; you should be able to see at a glance whether the test is running and how many methods have run vs total

Reason this comes up is if you establish a Unit Test run for your developer sandbox org, then you can't run (some) tests from your IDE against the same org "ALREADYINPROCESS Test already enqueued"

A quick glance at the Test Monitoring Overview would tell you if you need to wait 1 minute vs 20 - and guide your activities accordingly