#1
So I picked this schedule up somewhere quite a time ago ( Dunno where ) And was wondering if I should use it?
It of course helps with my playing, I see that, but should I add more time on some of these or add something else (playing or breaks)?

Here it is:
Warm up and technique / 15 min.
Scales and arpeggios / 15 min.
Chords and voicings / 15 min.
Sight reading / 15 min.
Theory / 15 min.
Rhythm and timing / 15 min.
Practiced material / 15 min.
New material / 15 min.
Ear practice / 15 min.
Open practice /15 min.

I added Ear practice just now actually

I'm taking a weeks break of guitar right now 'cause my wrist and forefinger starts to hurt too often when I start playing, and I wish to get the most out of my practice time when I start playing again.

Also, I wouldn't follow this every time I practice. Like everyday once this and then I pick some of these if I decide to play later.

And also... When practicing chords should I just learn one or two chords in a practice session?

Thanks
#2
I'd go for group voicings instead of just one chord, IE learn to play the entire 12 series of chords with that voicing then go over it. But thats just me.
#3
I think 15 mins is generally considered to be at the upper end of the concentration limit. I generally suggest somewhere around 8-10 for maximum efficiency with a 2-3 min break between each section. Otherwise yes you have a good system there.