I've been setting up my nurture flow and wanted to add wait steps between emails to stretch the content a bit longer.
I'm not that used to use Marketo, however i would assume that the lead waits for 1 week in stream 1 before being transferred to stream 2 with the current set up?
AFAIR, I've never used (or even heard anyone using) a wait step in the transition rule's flow. Most users have a single step to add people to the respective stream. I also don't think adding a wait step would stop a person from qualifying for the transition rules of stream 2 when they meet its criteria (email delivered in this case). Stream transition rules don't wait for the flow of other transition rules to complete before processing the qualified people.
I recommend using smart campaigns to manage the stream transitions instead, as those are more flexible than the stream transition rules.
You could create a transition campaign listening for email-delivered activity and in the campaign flow-
1. Change Engagement Program Cadence to Paused state
2. Wait for 1 week
3. Change Engagement Program Cadence to Normal
4. Change Engagement Program Stream to Stream 2
Pausing cadence while the person is in the wait step would ensure that they do not receive any other email from the EP while they are in the wait step. However, if your business case requires the person to continue receiving emails from their existing stream while they're waiting in the flow step, then you could ignore the Changed Engagement Program Cadence flow steps before and after the wait step.
Also, you need not add the advanced wait step properties for the sole reason of ensuring that the person does not receive any emails from stream 2 on non-business days as irrespective of the day/time the person gets added to the EP stream, they'd not receive any email until the next cast of the stream. Hope this is helpful. Please let us know if you have questions.