>>96803374 (OP)
Incorrect. I have autism-beamed over this for far too long. While games can be ran with a large or small number of players, the actual optimal party size is 5.
The meta-goal of a party is to be a group of characters that can play together on an adventure, interacting with one another and the world. In order for a party to be effective it needs to be big enough to cover a variety of concepts and abilities, but small enough that individual interaction and effort can be acknowledged.
Five is optimal because of the following:
Five divides unevenly into a 2 man and 3 man group, meaning that if the party splits up they are intrinsically in two vulnerable groups; necessitating close cooperation or else promoting rendezvous. On the other hand a split in 3 produces a solo group and a split in 4 produces two evenly sized pairs, so there is no 'weak' party that intrinsically is magnetized to the majority.
Five allows for the party to fill the four major adventuring food groups with a spare: A fighter, a rogue, a cleric and a wizard or equivalent selections cover all bases and allow for a duplicate or unusual character to fit in with only the bare minimum redundancy.
Five also leads the party to be, at least, numerically functional with an absence, and a sixth important NPC can be appended without breaking some mathematical assumptions that I collectively call 'stagecoach' or 'wagon' math. A party of 5(6) can all sit in a stagecoach or wagon (2 driving, 4 in the cabin) without any spares. Pairs can row canoes. They can comfortably occupy a 15x15ft room, or squeeze into a 10x10ft room, producing some but not excessive pressure in close quarters of dungeons.
I find other numbers are acceptable depending on the game and 4 is highly functional, especially for DND dungeon crawling as well. 3 and 6 respective for players begins to either limit function (and interaction, as no character can interact with another alone without producing a spare) or complicate running.
