I have two rhubarb problems.
One is a variety - forget what now but only just appearing this last few weeks - that produces lovely thick dark red stems which only ever grow to about 10cm long (if I'm lucky). I had to move it last year so took care to plant it at the correct depth.
The other is an earlier variety that seems to have two growing points. One is producing decent thickness and length stems, the other is producing quite spindly ones. This plant was an offcut of the thriving, nay rampant, rhubarb that grew in our school garden and it has been in place 5 or 6 years.
They are both in a fairly sunny spot in soil that is slightly alkaline.
Sorry to ramble on. Grateful to those who read!