imo, after a month or so of the finger fitness thing.. it pretty gud
Don't expect that you're going to get magically better or major improvement, but you can do on the bus/bored/waiting (ie. free time).If you r stuck in a wall, who knows it might help.
BARE MINIMUM, you arent going to get worse, if u get better at it, ur fingers r going to be more independent (technically its co-ordinated). seems kinda useless for 4k
Hardest thing is finger bends(like pinky and ring finger stuff), its not impossible to make progress with em, just some of em really difficult. Since u want it to be relatively smooth, not stiff