This is not correct. Your example 2 is already doable. After completing whatever you are doing (warmup, exercise, workout, interval, cooldown), you are absolutely free to choose whatever you like from explore tab. You are not forced to complete your full coach day before adding more.
You are also free to row before warmup.
Which OS do you use and app version?
And what’s the steps to reproduce?
I really often leave the coach tab between the individual units (I don’t mean the rest between rounds of intervals or god’s), jumping around, doing other stuff from explore tab - was never asked if I really want to finish my coach day. Unless I clicked on the button to finish without doing all the units or I choose something from another coach day.