Probably
Christopher
The repair manual says block the master with pointed sticks like pencils, the aim to stop air getting in. I tried cling film under the reservoir cap and can confirm that it did not work.
If you do the front then it is not much harder to do them all.
I'd you want help, and it is in the warm, I will come with a pressure bleeder and the correct spammers which I bought when I recently did mine.
It is a good time to change the fluid, two bottles of whatever you use is about right, one may be enough. Do the clutch at the same time.
Best wishes
C