Yes I do, clutch fluid always gets dirtier faster.
Change it when it gets dirty.
Google brake fluid though and educate yourself.
DOT 3 and DOT 4 are compatible and are both hydroscopic, which means it is able to absorb moisture. Some of the discoloration is water in the fluid which it is designed to change to a darker color the more moisture it absorbs.
DOT 3, and DOT 4 Brake fluid will just turn dark from sitting around with the cap off, thats why the instructions always tell you to add only fluid from a sealed container, preferrably new stuff. So don't go to the parts store and buy the big bottle to just top off your system.
It absorbs moisture from the air, and condensation from heat.
I still think they should have seperate reservoirs as a failure on one system could cause both brakes and clutch to fail.