I asked a native speaker who said it can be used either way, meaning length of an object, story or time.
Nagai requres +ku for negative form? What other types of words do too?
All -i adjectives do. Remove the -i and add -kunai.
All -i adjectives, I think.
All except いい、which is irrefular. You change the first い to よ and -kunai.
よくないです (negative present)
Is this used to refer to a long time or measurement of people/objects/etc?
It can refer to either distance or time.
If it was time would “It’s not been long?” be a correct translation?