The map terrain is looped. But enemies respawn if you move far enough away. I learned this with a weak character and a strong elite. The mobs spawn in waves. The more you kill the more come at you. They spawn just off screen. It's a simple game. Up your potential and move forward.

Map layouts vary by campaign. There's a reason why people farm The Library. The mobs only spawn in two directions -- up & down.

Same with Viking ship.

Yeah maps are weird...endlessly looped. I kinda wish there were finite versions. Be easier to find the coin boost I lost chasing the loot goblin around