This topic can be confusing sometimes, so I gave my best to explain it as simple as I could.
When it comes to SubD modeling you wanna stick to quad modeling with some exceptions on adding triangles in places where they do not cause deformations. Non SubD modeling, on the other hand, allows you to use any geometry type but has its restrictions.
P.S. Sorry about the typo mistake. It should say Motorbikes.
Hope you enjoyed the video.
Until next time,