Normal wisdom is that the input impedance of a stage should be at least 10 times larger than the output impedance of the previous stage. This reduces interaction and loading.

Hence while designing a -12dB/ Octave HPF by the very simple method of 2 cascaded RC filters, the second R should be 10 times more than first one, and the second C should be 10 times smaller than the first C (But the product of R.C should be same for each of the two stages)

This calls for a dual gang potentiometer where one part is 10K and other is 100K. That is hard to find. Some schematics suggest that the DIYer buys a Dual and 10K and and a dual 100K and does plastic surgery on them to get Dual 10/100K

I decided to see how badly would a second stage with a 10K resistor load a first stage with 10K resistor

On the left is a snippet of HPF from the VFE Standout and Focus pedals. There is a switch which disconnects the left part (R2 220ohms to ground) for 6db/octave and kicks it in for 12 db/Octave. It needs a dual 100k/10k pot

on the right is the same filter but with 10K pot feeding of a 10K pot ie dual 10k/10k pot, with a slight change of one cap value.

Red curve is original circuit of 10K RC filter feeding 100K RC filter

In blue are the 6 db/Oct filter by disconnecting one RC stage and also the 10K/10K filter that uses dual gang 10K ie not really ideal.

My personal conclusion : Of course there is loading due to 10K RC filter feeding 10K RC filter. But the final results are still suitable for the purpose of having a 6ish and a 12ish db/octave filter

(Oops I noticed an error in the left schematic. Lets see who spots it)