For those Lh semiquavers when the F# is repeated you SHOULD NOT pivot on the 3rd finger. You should move from 2 to 3 to 4 as you move up the keyboard with those 10ths. Actually look at the fingering here.https://www.sheetmusicarchive.net/compositions_b/btsn90.pdf
why not, I find it pretty easy to just stay with the 3.