Else if statement and add day function

Question

Here is some sort of e-mail reminder workflow.

The task is to create a workflow, that will send reminder 1 day before shift day, but the thing is to receive Monday shift notification on Friday(and not on Sunday), So I added a trigger(flag), every Monday will have that trigger and will send reminder 3 days before.

The question is, why workflow works with out "add day" function (it sends email at the moment, when the event was created), and when I add "add day" function, it gets terminated.

And I don't know why.

Please help.