Canon manual flash workflow

How do people quickly change their manual flash power?

I'm using a Canon R5 in a Nauticam house, the strobe is set to TTL and the camera is set to manual, which allows me to change the power setting using the camera. However, Canon had a clunky way of doing those, requiring that i enter the flash settings menu (i have customized a button to enter this menu), then select the flash power and finally adjust it. 

I would love to have a button to either enter the power adjustment, or a dial to change directly.

How do you adjust your flash power setting?

Which strobes are you using?

On, say, Inons or Retras, you can adjust strobe outputut - even on TTL - through a dial on the strobe. No need to go into the camera menu system.

I have two Retra strobes, but i would prefer not to have to adjust each strobe. Sometimes you don't want to jerk the rig around while shooting a skittish creature

I am skeptical you can do what you ask. This is likely only possible with dedicated Canon strobes that communicate directly with the camera so that the data can appear in the menu. Keep in mind that UW TTL is generally done via a third part circuit board, i.e. not in Canon's vocabulary. I have used three of the digital TTL strobes made by Seacam with Canon 1D series cameras (250D, 150D, and 60D) that all have dedicated wired TTL. To manually control these strobes in TLL, I used flash exposure compensation dialed on the camera body. In the case of the Seacam strobes one cannot use autoISO with TTL so the times I have used it there was no autoISO which is what I use a lot when not strobing.

I've not used the R5, I assume you have a TTL trigger with camera set to manual?  I expect you could also change your flash up and own by around 1 stop just by changing ISO  - with the R5 I would think there was little to pick between ISO 100 -400.  Unless you are moving your flashes around drastically, for close in macro the required strobe output should not vary a huge amount as the distance is not changing a lot. 

As long as you are well stopped down intrusion by ambient light would not likely to be an issue - you could also do this after the fact in Raw processing.

Otherwise there is probably not a lot you could do to avoid adjusting both strobes.  Other alternatives I could think of would be TTL using flash compensation in camera or you could have one strobe on manual output and run a cable across between the two strobes to trigger the second strobe on TTL - so that it mimics the output of the first strobe.  On S&S there is a fibre port to do this, on your retras you would need to rig up a cable holder so it can see the strobe output on the master strobe.  This way you only adjust one strobe output.