When I transcribe music for piano I always use the grand staff and notate the left hand (which often is the bass voice) on the lower staff, everything else on the upper one. When I do it for a guitar I find that one staff sometimes is enough.
What is the English name for these two methods? In Italian the first one is called "a parti late" and the second "a parti strette" which literally means with wide/narrow parts.
Most of the times on guitar (classical fingerpicking) you don't pick more than 5 notes at the same time and you only pick one bass note at a time that can't be lower than E (3 ledger lines is not that hard to read) so one staff seems enough for me. What are some pros of using the grand staff instead of this method when writing for guitar?