I do just about the same as fredehorn but a couple minor differences.
Parallel Taxiways
medium (and small if medium taxi need to taxi via) =
<-5 taxi-> <4 buffer-> <-5 taxi-> minimum (sometimes 3 buffer if I really need the extra space - however this is very very rare for me to do)
small (only) =
<-3 taxi-> <-1 buffer-> <-3 taxi-> minimum
Taxiway <–> Stand Clearance
medium =
<-5 taxi-> <-1 buffer-> <-2 service road-> <-Stand->… (so 3 tiles between taxiway and stand buffer)
small (if a large aircraft can transit the taxiway) =
same as medium
small (if no large aircraft will transit the taxiway) =
<-3 taxi-> <-0 buffer → <-stand-> … (GA CESSNA182 extra small a/c only)
<-3 taxi-> <-1 buffer → <-stand-> … (if no road need and/or I need to conserve space)
<-3 taxi-> <-2 service road-> <-stand->(if road needed and need space)
<-3 taxi-> <-1 buffer → <-2 service road-> <-stand-> (if I have lots of room and need the road there for vehicle access)
not sure about the large aircraft yet…
Hope that helps @alexwonglk