A select group of minor scales (melodic form) have ENDS that need particular attention. That is, there are fingering ALTERATIONS that must be made to SUIT them, creating a better fit for the hands, and a smoother line from start to finish. (A SEAMLESS pursuit) Not to HEM and haw about them, but they require specific practicing techniques that would be considered the means to the ends.
NOTE that in all melodic minor scales the 6th and 7th notes are raised a Half step, respectively from the Natural form of the scale when ASCENDING. On the descent, the scale returns to the natural form without the raised notes.
Examining the C# minor scale in 10ths..
The hands play a tenth apart, but even if they were a matched pair, going up and down from root to root, to root, to root, etc. in 4 octaves, the fingering would change in the RH when the scale came around the corner and descended.
RH (root position) Using a two octave model
Going up C# D# E F# G# A# B# C# D# E F# G# A# B# C#
2 3 1 2 3 4 1 2 3 1 2 3 4 1 3
B natural A Natural G# F# E D# C# B A G# F# E D# C#
2 1 3 2 1 4 3 2 1 3 2 1 3 2
At the top of the scale, A# B# C# (I use 4, 1, 3) so I can careen down from 3, to 2, 1, etc. without a hitch?
Rather than belabor the LH fingering which keeps 4 on F# ascending and descending as a matter of habit, form, and practice, I will shift over to playing the scale in 10ths which attaches a detailed video about how it’s done. Here again the means justify the ends, so having good exposure to the scale in parallel root to root to root motion. (assists the player in part) But notice the terminus of the RH on the last five notes (A#, B#, C#, D#, E) and how blocking is a practicing asset to smooth out the total journey up and around the corner. Blocking also suits the LH as well–(demonstrated using separate hands in my video)
NOTE That the start of scales often attaches a slightly altered fingering.
In C# minor if starting on the root, 2 is preferred to finger 3, since C# D# E, 3, 4, 1 would be awkward and might impede speed. (Hence 2, 3, 1 works better and matches up with LH, mirror fingers 3, 2, 1) In tenths the thumb RH falls naturally on E–so E F# G# accords 1,2,3.