Hi Joe, welcome and I'm glad you're finding the process intuitive so far.
Currently that is the way the sequences are built. As you've mentioned, the best way around this would be to include a pause between each of the 'call sequence' steps.
I could look at adding this as a new feature. I would imagine this being an option when adding a 'call sequence' step that you can select whether the initial sequence continues to run or waits for the other sequence to finish first.