Theoretically, I agree with everybody who's said the teamwork stuff. However, in my limited experience, I've preferred the single pharmacist. Where I work, it's just one pharmacist 9am-9pm, alternating days with another one. Everything seems to go pretty smoothly, although they've both been pharmacists for a while, so I'm sure that plays into it heavily. We close 1/2 hour for lunch as well.
On the other hand, I had an IPPE with a 900+ rx store that had anywhere between 2-4 pharmacists depending on the time of day with overlap. It was pretty chaotic, and I could definitely see people stepping on each others' toes. You call about a script, leave the doc a message, somebody else takes the doc's callback, fills the script, you're left wondering. Or they take the callback and have no idea what the call was concerning. And there are always some differences of opinion/professional judgment/whatever, and things get sent back and forth. Plus side, you can always take a break whenever you need it, or if you get hung up on something, other rph are covering other work.
I'm sure on the grand scheme, teamwork is better, just hard to see it from my experiences. I really can't answer from an rph position anyway, where I would be the solo operator or the teammate, so take it all with a grain of salt.