The earth has something like a band of land thing happening around the Arctic Sea, you can see between iceland, the UK and Norway the ocean is shallower and deep around the Arctic and in the Atlantic. So I disagree that it’s an unusual feature.
I also think re ocean depths have a look on google earth, you can see there are areas of deep ocean and other areas (North Sea near the UK, the Sea north of Russia, the sea around Indonesia and north of Australia etc) which are shallower over huge areas. So I think it’s totally normal to have oceans / seas of different depths.
I think in general it’s much more powerful to pick out interesting collections of patches which will make nice, variable, play areas than it is to try and sort of average a planet into patches.
Edit: This is also quite interesting, if you look at an elevation map of Mars and you imagine it filled with water there would be a large ocean in the Northern Hemisphere and then a large continent in the Southern with a massive sea / ocean trapped inside it.
Edit 2: Another thing I think is interesting about planet is what percentage of the surface is covered in water. I guess if 70-100% is covered in water (Earth has 71% I think) there might be a lot of large oceans all connected to each other. If 0-30% is covered in water I guess you might expect several smaller, shallower, oceans which are less likely to be directly. It’s not something I’d really though about before, how water percentage impacts patch connections.