What is the "preferred" method of plumbing main drains and skimmers? Assume two main drains and two skimmers.

1) Main drain #1 plumbed to skimmer #1, which is subsequently plumbed back to pump suction. Same arrangement with set #2.

2) Main drains plumbed together and plumbed back to pump suction. Skimmers plumbed together and plumbed back to pump suction.

The pool will be equipped with an auto fill system, if that makes a difference.

Also, how many separate return (pump suction) lines should be run back to the equipment pad?

Thanks ever so much.