Unlike the usual stack system that grains and other seeds use, crops such as Beetroot and Carrots stop planting when you use the Shift + Right Click feature.
Sometimes it plants by x4 tiles, sometimes does a batch of 16 tiles, other times only one (especially if the stacked item only has 1 item in it).
There's already a working stack feature used by seeds, so why not make other crops use the same one?
I hate it when I switch to another tab watching Mario Cart and then find out that I haven't planted the entire field of Turnip.