Trying to figure out the upgrade system

There are 3 important components in the game:

• A list of resources that have a maximum amount (can’t have more than 100 pieces of wood in that little shed).
• Players with gathering skills with rewards (pick a stick, get wood).
• Helpers with gathering skills that have a speed, requirements and rewards (takes 1 second and 1 food to get 1 wood).

The player gathers resources on the map while the helpers gather resources over time.

The old upgrade system worked that way:

• Increase resource maximum amount with other resources (build a shed with wood).
• Player and helper gain experience point each time they gather something. The experience point would be specific to that gathering (gain xp in wood gathering when gathering wood only).
• Players could use that experience point to reduce the speed, reduce the requirements or increase the rewards.

 This ended up looking a bit like a mess on the UI and I had trouble figuring out the algorithm.

I decided to go a bit simpler for now. Only focus on these aspects:

• Increase maximum amount of each resources
• Decrease the speed of gathering
• Increase the chance of getting twice as many resources

That way, I don’t need to mess with percentage of requirements or rewards. This would also make player and helper use the same upgrade system (since a player does not have requirements).

Also, after adding planks (which are built from wood), the word gathering doesn’t make much sense and I’ll try out the word “work” instead.

With these 3 upgradable aspects in the game, it ends up making everything the same. This is good for the programming side but a bit boring on the game play. Now I have to think of a way to add specialty to each. What sort of skill can a woodcutter could have?