Although I have not "lashed up" several engines on my DCS system, I wondered how close each engine speed is, all things being equal. In other words, If I put two different MTH steamers and a diesel on the track (or maybe three of same model numbers), not coupled together and separated several inches between them, would the whole consist move evenly or would engines begin catching up or falling behind after several/many laps around the layout? Thus latch-up engines could begin gradually pulling or pushing ones in front or behind. I realize that there are variation in manufacture etc which would account for speed variations, nothing's perfect.
Obviously this is more academic and probably moot, as MTH and operators would have noticed this problem by now if it was bothersome. Ditto for Lionel engines.
Probably same thing in the real 1:1 world that same model/type engines in consist would not all move evenly in same run position.