A noticeable exception would be add-ons for the TrainCart plugin, which may change the (relative) position a sign would need to be placed on in order to work for the track. For example, would the TC Hang Rail add-on require you to add the signs above the Hang rail track to work, while the TCC (TrainCarts Coasters) add-on uses the block of a node for the sign, which can be moved to any other block.