The first time you create your Retreat, since no information has been created yet, all the 4 steps will be necessary. From Creating the Bedrooms to Creating your Business information.
Once all the 4 steps have been done once, you can choose to create whatever you need.
For example, if you want to add another bedroom type, you can just create your bedroom.
Or, if you want to add some availability dates to your Retreat, you just go ahead to create your availability.