@Karen4374
You're right that you can directly connect the calendars of different portals. I did that for many years. However, the synchronization between the portals often didn't work properly, so I had to check regularly to ensure everything was correct. With one property and two portals, that was still manageable, but it became more complicated when I started advertising on more portals, making me feel uneasy.
When I acquired a second property, I decided to invest in Smoobu. An additional benefit is that I can centrally manage the prices in Smoobu, which are then automatically sent to the portals. That advantage is minimal if you work with fixed prices throughout the year. However, since I work with seasonal pricing (about six seasons), managing everything centrally saves me a lot of time and effort.