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?

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.
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.