It depends on the size of your house and the amount of dirt and dust.

Maybe, but only if literally everything else is the same. Otherwise it could just mean that one place is cleaner than another, or that one vacuum has a big bag and needs to be emptied less frequently despite picking up the same amount.

• Roborock bag size is 3L (6"x6"x5"), so think 1 and a half 2L soda bottles, since it doesn't need to fit inside a handheld vacuum or a moving robot it can be this large. Comparatively, the Matic bag which you can see in the video looks super tiny.
• My apt is ~500 sq feet, so "1 time around the house" isn't very much
• How many dirtying factors apply to your house?
  • Pets going in and out track in extra dirt, our cat is indoor only and only sheds some fur (I didn't have the cat when the dock bag lasted a year so we'll see how that impacts it)
  • Allowing shoes to be worn inside tracks in a lot of dirt - so we don't allow shoes past the entrance shoe rack
  • Going in and out more times allows more dirt to be tracked in - I work from home so I don't need to go out every day which greatly reduces the amount of dirt tracked in
  • Living with more people multiplies those many times over, for me it's just me and my partner
  • Ground floor apartment or elevated - another factor since going up flights of stairs lessens the amount of dirt tracked in. Our apartment is up 3 flights of stairs, so by the time we get to our front door, most mud and dirt has fallen off our shoes. If you live on the ground floor, it's more likely that dirt and mud can hitch a ride in the treads of your shoes

So it really makes sense that my dock's bag doesn't fill up quickly. I can be absolutely sure it works because it produces gray mopping water every time it's run, and there's not a speck of dust or cat hair on the floor after it runs. I can check the bin on the robovac after a run and see it 1/3 full of fur and dust, but the bin on the robovac itself is on the small side so once it empties into the dock it seems to barely add much volume - and I suspect that the dock's vaccum is powerful enough to compact fur and dust into the bag somewhat so it takes up less volume. And that makes sense because the S7 has some of the best pickup performance as rated by vacuum wars on youtube, but I can really stretch the dust bag in the dock both because it's a whopping 3L bag, because I do everything I can to prevent dirt from being tracked in in the first place, and also because some of the dust is mopped and flushed down the laundry room drain without ever seeing the bag.

Yeah the ultra dock is amazing, I got the mop dryer and water change kit addons, so it auto refills the clean water tank from my washing machine water line, and auto empties the dirty mop water out a tube I stuck down the washing machine drain. I used to have to refill/empty those water bins every week but now the most frequent maintenance is rinsing out the water filter every 2-3 weeks. Everything else seems to be only required monthly.