Just in reply to this
We had a hard time determining what lengths are sold in the rest of the world, so if 2.4 m and 3.0 m are incorrect.
Short answer is, whatever lengths (of whatever it is) that can fit inside a shipping container, minus a bit to allow for handling.
For a 20’ (6.10m) shipping container the internal dimensions (in meters): 5.898m long x 2.352m wide x 2.393m high.
Which results in everything here being 5.6m long (timber/lumber, steel, aluminium)
Do they sell it in shorter lengths too, or is that the only length which is available and you have to cut to size if you want shorter bits?
In my experience here, that’s the only length. Having said that, most of the hardware supply stores (but not all), will let you cut it to size, so long as there is a reasonable length left over for sale.
This usually does not apply to timber/lumber. But Aluminium and Steel it does.
in Europe (Belgium) 2x4”s are actually 38x89mm. they come the lengths of 2m40 up to 6m00, in 30 or 60cm increments. 2m40 and 3m00 are easy to get.
price per meter is usually identical.
2.440x1.220mm is still standard for many types of plywood although lengths of 2.500 and 3.050 and widths of 1.240, 1.250 and 1.530 are becoming popular.