Attic storage - How to lay tongue and groove boards

Good morning everyone!

Our house is currently in the shell construction phase, soon the insulation of the upper floor along with the installation of the boarding in the attic will take place.

The distance between the individual rafters is about 60 cm, which thickness of boarding should I choose? 22 mm or rather more?

Yesterday I had an idea, but I do not know how sensible the whole thing is.

The area to be installed is about 3 m wide and 12 m long.
In the "normal case" you would install it as shown in Picture 1 (red = rafters/beam, blue = boarding).

Due to the width of 3 m, it would be significantly easier to install it as shown in Picture 2.
Buy/cut the boarding to one length (just under three meters) and install it.
Then with counter battens (green)

Which option is more stable? I suspect option 1, right?
How thick/sturdy do you think the battens would need to be in option 2?

Thank you very much for your opinions,

have a nice Sunday!

1). Applying the counter battens is 2) no less complex. C.

Well, basically I believe that it is easier for me to install a counter batten than the final tongue and groove.

For me, the question was mainly about stability, that is rafters vs counter battens.

Anyone have an opinion on that?

Regards

That depends on how thick your Lattung is.

okay, and which latten-thickness would you recommend?

So about 50 times 45 or 50. I myself would choose option one without the battens. That’s also how our floor is made. It’s quickly nailed on there.