Senecio rowleyanus

Is anybody able to answer my query. I have a Senecio rowleyanus that is trailing nicely at around 2 feet long. It lives in a south west facing window, receives sun including at top growth level.
However the ‘pearls’ seem a little small the further down the stem they grow. Is this normal? If not, what do I need to do to maintain/correct the optimal environment for this plant?
As you all know, it is difficult to find really helpful and consistent information via the 'net

Many thanks