Hi Anthony,
You can hold a posture for as long as you want as long as it is comfortable. How long you hold a pose is often determined by how much time you have. If not a lot of time, maybe one breath. If more time, maybe 3, and if there is no limitation 5 or whatever.
The breath is a good way to gauge how long you stay in a pose. One breath for one person might be 20 seconds and for another 4 seconds. Depends on how they regulate or don't regulate their breath. Five breaths for one practioner could be 10, 20 or 30 seconds. It is not rigid. It is flexible and not either/or. You can adapt the poses and breathing to yourself and what is natural to you.
The sun salute poses can be gone thru from one pose to the next without pause, like the lady in the video is doing. It is more of a warm up for an asana session. But each pose can be held for period of time before going to the next pose as well.
There are different standing pose sequences that can be gone thru, one pose to the next, without pause in the same way.
There are many different approaches to asanas by different practitioners. Some asana aficionados might hold a pose, the forward bend for example, for 5 minutes because they want to have a particular effect on the soft tissue.
So how you practice depends on what your goals are, how much time you have, etc. There are no hard and fast rules unless you are trying to learn or adhere to a specific system. Sounds like you are adhering to Yogani's guidelines.
But the number on rule is to always stay within your comfortable capacity, what ever method you are using.
Hope that helps.
Best, yb.