Firepot: After every cook regardless of type of cook. Except when I do not feel like moving my grill grates off then it is every other cook if I am just grilling with them. This is generally because of my issues with the auger and temp. With my other brands of pellet grills I only did this about every 5 or 6 "grills"s but definitely after each long smoke. Which is why I like the weber because it is so easy to get to .
Ash Box. As needed. If it is greasy then I try to do it before the next cook. FWIW I have done a 19 hour Brisket cook and not had a quarter of as much ash as you though! Thats a crazy funny pic. Plus more of my ash ends up in the tray than it does in the little box.
Bottom Drum: IF I see heavy grease I will sweep it out. If it is just ash I generally leave it in there for several cooks until it builds up and then I gently sweep it. Im kinda old school and this "seasoning" use to help seal up a smoker (my WSM never ran right until the seasoning built up.) The Smoke fire does an amazing job of not blowing this ash into my cook box so I really do not care as long as the grease ports are clear.
Cooking Grates/Grill Grates Every single time. And no I do not scrub them back to the original. I want them like a seasoned cast iron skillet with an even layer of carbon deposit.
I use drip pans and so it doesn’t get very dirty. Just ash. And I’ll vacuum it out like just about every time I use it. I did not use drip pans once when I did ribs, and it was a huge mess. Won’t do that again.
After long cooks I use scraper in the barrel and firepot. If short cooks It just depends sometimes I go ahead and clean it out sometimes I wait. It doesn’t take much time to pull grates and push ash/grease into the drip tray.