Big/big plus one inch is fine if you're using the biggest sprocket that you every plan to run. If you set the chain length with a 28T and later change to a 32 or 34, then the chain will be too short. The longer length will work with any of those sizes, unless you're deliberately exceeding the RD's wrap capacity.

To get that length, use the little/little and make the chain as long as possible without hanging loose. As long as the RD moves forward by a small amount when the ends are joined, you have the length needed for any cassette within the RD's wrap capacity.

If you're deliberately exceeding the RD's wrap capacity, then the big/big plus 1 inch will give a chain length that will hang loose in several of the smaller cogs.

FWIW, I've used the same chain length on all of my road bikes, with largest cogs from 25-32T and 53/39, 53/39/28 or 50/34 cranks. Of course, all setups are within the RD's wrap capacity.