There is a longstanding image of budding guitar players working away for hours on end to master their instrument. Hiding from the outside world and playing for maybe 7 or 8 hours straight. Is this an effective way to practice? If the guitarist has thought out what they’re going to work on and allowed time for breaks then yes. There is no magic answer to how to practice, I say you should go for what works for you and try and take ideas from how players you admire practice. The main thing I’ve learnt is that it is better to work on something for a maximum of 20 minutes and to then have a break. If you have an hour or half an hour a day to practice then try and break it down into chunks. It could be something like this:
0-5 min Warm-up
05-20 min Scales/arpeggios
20-40 min Song that you’re working on
40- 60 min Improvising
What’s important is that before you even strum a chord or play a note, you know how you’re going to use your practice time. It’s far too easy to waste time playing something you know inside out! Next time you practice try and break your time down into 15-20 min sections. Playing in short bursts is also sensible as it helps avoid any annoying strains or pain in the right arm/wrist.