The adjacency bonus applies to all adjacent types next to each other. It also applies vertically. So, if you have four workshops in a 2x2 configuration then you will get four "adjacent" bonuses or a 28 percent return. Note that for workshops you get the rebate at the end of the job. I am putting in a 2 by 6 workstation complex that will yield a 49% rebate.
Also, for up-links if you want full satellite coverage, you'll need a capacity of 18. That will be three nexus stations all touching in one way or another.
It is worth while building the efficient power stations and then moving the pre-built facilities to more efficient configurations. It takes a while and you won't be able to do it all at once. But look at where your best steam row (or column, don't forget that you can plan this strategy in a vertical configuration too) is and plan for that to be your generator row/column/box. You may have to build some facilities in temporary locations in order to maintain full power but with some planning you can minimize this. Also don't forget that it takes a while to excavate so, do this when you can even if you're not planning to build right a way. I have found that keeping two spaces open for future development is a good practice. At least this was possible at "Normal" difficulty. One may find resources too limited to do this on higher difficulties.
My top two rows are all the specialty facilities as there will only be one of each of these. Also, don't move your Officer training school as you will lose your OTS upgrades and you'll have to repurchase these after you've rebuilt your OTS. -- This last bit is not correct. The upgrades come back when you rebuild your OTS.