in Audacity you have a nice option with which you can repeat the effect you last applied. this is a lot faster than just re-selecting the desired effect, because the effect often has a little interface with settings etc. if you know you want to apply the same settings to your selection again, you do a Repeat.
in the Renoise Sample Editor you have only one (relevant) option which has this pop-up settings box, and that is the Volume Adjust option. now, say you adjust the volume down by -1dB, but you still think the sample is too loud. so you want to adjust by another -1dB, and again and again and again and again and again. it takes you two clicks each time: Adjust Volume > Process.
currently right-click does exactly the same thing as left-click. so therefore i propose to make a right-click on the Volume Adjust a ‘repeat with current settings’ option, making it one-click, as are all the other (relevant) buttons.