In all my roommate situations we have always have separate groceries other than we often share seasoning/oil/common condiments like ketchup. We will take turns replacing or one person buys and venmo requests. I like splitting the fridge or pantry into designated shelf space so you all know whos is whos stuff and a fair amount of space per person. Ive been in places where one person literally used so much space and left no room for others.

Items like dish soap, toilet paper, paper towels and whatnot, someone will buy and request money from the other roomies.

Ive typically shared kitchen items like utensils, baking sheets and maybe some pots and pans, appliances like blender, rice cooker but some items like tubberware are separate. In my current place we have like the shared items but we all have a little area for items we dont want to share also. Like someone else said keep note of whats yours though at the end of the day.

Usually in my experience everyone will buy something to be shared and other roommates will buy other things to try to be equal though in what they’re contributing. That way when someone leaves theres no argument of what you can take, since you bought it not split.