[pman626]

I'm resetting my tile roof, which currently doesn't have batten.

i will be putting batten over shims so water can escape underneath.

I have seen video that says to fix the tile by nailing through batten only, but not past the sheathing.

What is the standard practice? nail through batten+sheath, or batten only?

 

[chandler48]

Nail through substantial batten only. Plywood (decking) doesn't have the holding power that dimension lumber has.

 

[carpdad]

Did the video explain why? A layman here about such roof and asking why would that matter?
One idea: not making more holes than necessary. If budget allows, and tile roof usually is a big budget item, take extra insurance by wrapping the WHOLE roof with ice shield sheets. Just speculating: I would cover with ice shield sheets. Peeling off the paper backer not necessary. Then cover with tarpaper and staples so it's easier and less hot to work over. Use some capped nails if wind is a worry. Then while the roof is protected do the tile roof taking your time.
Is this diy? There were past posts about LOT of water draining under the tiles. Search and study tile roofing so you avoid some of these problems.