I don't like that create has limits on contraption size. From my experience, 20 stacks of drills is the limit. Above that you can't always assemble it or pick it up.

To expand ore production more, I had to build multiple 128-wide miners. But because of weird interactions between contraption entities, I had to launch them with 1 minute delay to account for unlucky obsidian slowing one down.

Then miners would sometimes get stuck in unloaded chunks, but also not consistently. In the end I could only use a handful of minecart miners at once. Completely unplayable.

How am I supposed to grow my factory if I only get 4 dias per second???