Those with Groms and other similar bikes- Why do you own a Navi too?

I love my Navi- but I noticed there's a lot of responses on this navi forum about people mentioning things like "My Grom gets better fuel economy than my Navi" and similar.

I see the appeal of the Navi, but I'm just curious- if you had groms or other small fun bikes, what is the reason you also have a Navi? When do you choose to ride the Navi over other bikes you already own?