I have rigs tied up for all depths (with a one foot spacing), found the beauty of that is, that if windy and towing for example and i am fishing a 4ft part of the swim, out comes the .5g rig, giving (.1g per foot rule) me that extra bit of line between tip and float needed in conjunction with the bit more weight.
I tend to do my deck rigs the same length of my top 2 kits, margins an arms length same with carp shallow rigs, f1 shallow rigs are precisely made to the exact depths I want to fish. If I'm going somewhere I know will be deeper I'll make rigs to suit that venue. River pole rigs I do the same length as my top 5.
I have one rig tray for deck rigs, top row carbons and bottom row wires, all slims.
Theres approx. 14 or so rigs in each row and each covers all depths from a foot up to 8ft (commercials only). I have found I can pretty much get by at most venues with these, I do however have a few deep rigs set aside elsewhere for those pegs over 8ft.
Tie a rig the full length of your top kit whether that's a 2 piece or match top 3.
Starting with an 18cm winder put the rig on and count the number of turns round the winder. If it comes to say 7.5 complete turns then write it down on a piece of paper.
Do the same with your next section added and write it down on a piece of paper.
If you have some longer floats that need a longer winder like a 20 or 22cm winder do exactly the same and write it down on a piece of paper.
I think you can see where we're going here.
Counting in arms lengths is daft. You could be built like Peter dinklage or Peter crouch!