I2C Put One Termination Res at the End or on Each Slave Board
You can't just put a pull-up on every board: Your I²C devices need still to be able to pull down the lines, so if you increase the up-pulling by adding more boards, you're making it harder for the I²C devices to use the bus.

Then, adding more boards even without pull-ups on each of them will increase the capacitive load on the bus, up to a level where the bus might simply no longer work, because any one of your chips might no longer to pull down fast enough.

The solution to that is using either a more robust bus (CAN comes to mind), or redriving the bus every couple of boards. With I²C being a bidirectional bus, this is pretty complicated. A solution might be to limit the numbers of boards per bus to something benign (depending on your cable length and boards and chips), and then using a bus extender to drive multiple buses in what will look more like a star architecture than a daisy chain.