Co Gamesmastering

 There is a trend, I've noticed, in splitting up the role of the gamemaster, so that less mentally prepared gamemasters can still run the game, without having to do 10x as much work as the players. At first I was like, NO! (as a backlash to GM-less games) but then I understood, I've always done this. 

Ways to Co-Gamesmaster.

The Gamesmaster runs many roles, For me the underlying plot points, major NPC actions behind the scenes and how they affect the other NPCs that interact with the players. Economic flows of goods, services and information based on NPC actions and player actions, often less dominant for shorter 3 month campaigns, but are almost vital to immersive roleplay with longer campaigns, often done by the GM between campaigns.

Then the more nitty gritty, crunchy subsets of individual NPC motivations, how to roleplay those NPCs and this includes BBEGs as much as the minions, townsfolk and random encounters.

Yet some GMs I find, are so bogged down in other aspects of the game, they don't have time for the above; instead combat, maps, dungeons, gear tracking take up their time. None of these need be done by the GM. Lets look at ways to break down the components of the game for players to be more equal in the games tasks.

Combat

Often there are players who are one-trick wonders, spell casters, healers and some rogues, just are not built for ongoing battles. These players are left wanting at the table, causing games to even change their rules to be more inclusive, breaking the basic world rules, in an attempt to give all players something to do each round. (most DnD spells, in a town setting, can be used to advance economies, so why risk life and limb, when you can be employed locally to work your magic)

Get these players to be in charge of the monsters, they'll pull punches, and let the heroes win, but the GM can play as the boss monster to balance it all out. Everyone is involved.

Maps

Vice Versa, when combat is done, and the barbarian is just walking along with the group, unable to swing their sword, maybe the player can sketch out the map, drawing out the GMs descriptions of corridors and rooms, and if they get it a little wrong, well more realism, more immersion. (all players can contribute, to avoid, if need be)

Rules Lawyers

As often as not, players don't have the time to be looking up spells, components, prayers and effects, players not engaged with the rooms traps or secrets, might glance through the rulebook, looking up how they'll level up, or what spells they'll need for the next room. In real life, when someone is taking charge and looking around a room, others saunter in the corridor, or stand by the door, ready to leap out when a trap triggers, while they stare off into space, have the player pre-prepare some skill calculations.

Dungeons

As often as not, a dungeon can be created with random tables, maybe the player would like to be the dungeon designer this session. DD12 has a clear and fairly simple set of rules on how to develop a dungeon, without going overboard in monsters or treasure. Often a side lair is a good little random encounter on the path from town to the main quest. Players might pick up some extra treasure, and a scratch or two. Let your players learn the ropes, by making one of these lairs.

Bards Tales

Some players like to track the details of an adventure, jotting down the notes of each step along the way, helps in many little ways. The following week, when trying to remember the events for experience, a quick handy list helps remind everyone of where they are in the plot, what's coming up, what not to skip/miss and gets the group into the game a little faster.

Logistics

Have a player track all goods the party has, but also, approx. how much it was purchased for. In real life, we often remember these little bits of information, because we remember the whole path, picking out the goods, seeing the price, going to the shop keeper, maybe a discussion, then handing over the coin, taking the goods home, glancing at the receipt maybe, opening the goods. The whole process is flushed away in roleplay, and just the object is written on the character sheet, and the coin deleted. Having this info written in the log acts as the players memory of those events.

NPCs

When an NPC is not vital to the plot, and a PC's character has retired for the night, or is incapacitated, or in another scene entirely, don't have them bored waiting for their turn, hand them an NPC card, with some motivations, ideas, and possible skills, and get them to do the interaction. Shopkeepers, Urchins, Salesmen, Gate Guards and more, are all fairly common NPC tropes, let the players roleplay together, while you watch as the assassin from the rooftops.

Conclusion

So yes, the GMs role is huge, if you want to do it well, so why not split out many little tasks for your players.