I've written on this subject myself (see link below). Personally, I think an intermission is a courtesy with films above a certain length, but I prefer it when directors design a film around the intermission, like David Lean did with Lawrence of Arabia, or more recently Brady Corbet with The Brutalist. By contrast, Schindler's List is a film not designed for an intermission, nor would I want it to have one.

Intermissions: Invaluable or Interminable? | Fanfare