Board Game Arena

Can someone write up a player guide for how the chining works on the board? I do not get it. Sometimes I get only 2 when I think I'll be getting three.

My understanding is... it's the quantity of new numbers in a chain. I will give some examples.

You have a 1 on your board.
You place a 2 next to it.
This forms a chain of 1+2.
Both numbers are new to the chain, so you get 2 actions.

You have 1+2 on your board.
You place a 3 next to the 2.
This forms a chain of 1+2+3.
But the only new number in the chain is the 3, so you get 1 action.

You have a 1 and 3 on your board.
You place a 2 that touches both of them.
This forms a chain of 1+2+3.
All 3 are new numbers in the chain, so you get 3 actions.