Your training should focus on specific topics, not a bunch of random things combined together.
20 minutes of "study" here and there is ineffective, in my opinion. Also, playing variants at blitz time control (or chess in blitz time control) should not be part of your training.
***The general idea of training:
Your goal should be to get new, useful knowledge (for instance, "safety checks" before your every move) and implement this new knowledge into your thought process via slow games, where you can think about what you should think about 
because you're trying to make deliberate changes to your thinking process that will be uncomfortable (hence you need slow games) yet will eventually integrate itself into your thought process, and you will find that your playing strength improves as a result.
Hence - part of your training could consist of a 30+5 game, where your emphasis is on safety checking. After your game, you should analyze it yourself, and then use a computer to look at it, and see what mistakes you made. Did you follow the thought process you wanted? If not, why didn't that happen? In the future, you will be better at using this idea.
This isn't everything about training, but a 30+5 game per day where you do "safety checking" - basically asking yourself before every move "is this a tactical blunder?" and scanning your opponent's possible replies carefully, and then analyzing the game afterwards with a computer will be much more effective than what you have.
By the way, if your blitz is <1300, you're a beginner, and you almost certainly don't do safety checks in your games, and make tactical blunders that the opponent can exploit.
So actually you can do what I said right away, and it should be rather effective.
Also, there is one *fundamental* rule in my opinion, concerning engines, since they are so widespread nowadays, and easy to misuse:
***The use of an engine is to keep you objective***
This means that you need to come up with ideas yourself, and the critical use of an engine is to *verify* your ideas. If you become biased, you are hurting your own chess, so an engine can help you here - keeping you objective. If your idea was right, take note. If it was wrong, then investigate a bit further - and understand why it's wrong, and learn from that.
At the moment, I usually hover around 1200-1300 when it comes to blitz rating, which would put me at around the beginner-intermediate range. The reason I play blitz despite the obvious drawbacks is because I usually underestimate the amount of time I have, and end up playing long blitz sessions, which can be harmful to both your rating and to your overall chess strength as a player. And at the same time, when I play longer rapid time controls (usually on another site), I sometimes don't have enough time to finish a game, thus devaluing the game for analysis.
I've never really stuck to a chess study schedule before, but that's not going to stop me from trying. Ideally, I would love to adjust my study schedule to less than 90 minutes a day, splits into two separate sessions (morning and afternoon).
This is my proposed daily schedule for chess:
Morning:
(30 minutes) "20 Minute Drill" https://www.youtube.com/watch?v=XkI5zsVX6i4
Evening:
(20 minutes) Opening Study
(20 minutes) Tactics https://www.chess.com/article/view/the-legendary-15-minute-drill
(20 minutes) 5|5 Variants (Crazyhouse, 3 Check, Bughouse, 960, King of the Hill) + Analysis
I am 14 years of age. Is this schedule too challenging or too easy?
EDIT: I will also play longer time controls on weekends.