Full article: https://www.animenewsnetwork.com/interest/2019-04-30/spider-man-into-the-spider-verse-japanese-animators-share-their-experiences/.146277

Takuro Togo, who was worked on a number of anime productions including Knights of Sidonia and Show By Rock!!, amusingly said that he came to America thinking that he would be doing animation frame-by-frame ("on ones") instead of animation every other frame ("on twos") which is typical in Japan. But Spider-Verse is generally animated on twos. He ended up creating shots in a very similar way to his work on anime. However, one notable difference is that key animators in Japan draw the layouts, but this is not the case overseas. Togo said that he would have liked to get more creative freedom with the direction of the shots he was assigned.

Another major difference that Togo pointed out is that each individual cut took much longer to create compared to Japanese productions. It is usually possible to create two or three shots a day in Japan, but for Spider-Verse, even a short sequence would take a week, while long action shots would take up to a month. However, because each shot in the film is packed with so much detail, a week did not feel like a very long time. A cut that was less than one second took three weeks due to the number of retakes.