Project to show timing difference in Scratch using the wait block and using the Days Since block. The wait block causes your script to yield processing to the next script. When there are no more scripts in a pass through all the scripts Scratch pauses for an animation delay if one is required. It does not check to see if the wait value has been satisfied until after the start of the next pass through all of your scripts. Normally the scripts start processing on intervals of 1/30 of a second, so any wait value less than 1/30 will have been satisfied by the time the script is restarted again at the wait block.
Look inside to see how to accurately wait very small amounts of time using the Days Since block. The license for the cat's head is in the public domain. https://publicdomainvectors.org/en/free-clipart/Cats-head-with-blue-eyes-vector-image/29116.html Clock Face: https://www.publicdomainpictures.net/en/free-download.php?image=clock-icon&id=71182 License: CC0 Public Domain