When I was play testing it, I was working with around 3 seconds, but I couldn't imagine that to be doable and I didn't want to make it so other people going into it wouldn't be able to combine them since the dragging is still a little finicky. It's a hard balance. Usually I do it with by being lenient but I can see it backfired this time, considering the theme.
The reason why you could zoom was because I was trying to solve the problem of the card not being visually clear that the resolution and card size.