If you have a true bypass wah on the ground in front of you and a 20+ foot cable going back to your effects rack then try using the buffer both before and after the wah.
If you have a true bypass wah on the ground in front of you that's plugged directly into a floor based multi-effect that's right beside it then you shouldn't need a buffer.
If your guitar is plugged directly into your effects rack you shouldn't need a buffer.
If you have a wireless or are using EMGs you definitely don't need a buffer.