I'm unsure whether the above mentioned sites tackle the issue in a similar fashion or not, but something that I (so far) succeeded with is determining a clear goal (can be both short- and longterm) and working towards it with a schedule.
To give you an example, I'm participating in a tournament in mid September that I care a lot about and essentially have to win to not ruin my ego. I qualified for it around April, and created a schedule to prepare for it in the upcoming months starting from May until the end of August.
With four months to my avail, I decided to spend a majority of the time on what is probably the biggest cornerstone, which is footwork. I've had two entire months of heavy training with footwork multiball drills (2-2 for starters, 3-P Forehand and Falkenberg are probably my favourites) and all I can say is that it DOES pay off if you do it regularily. It's no use to play a drill once every second week. You gotta do it every single training session, and preferably practise atleast twice to three times a week.
After the footwork I decided to introduce a couple more realistic, close-to-match drills and work on my service, return, as well as opening up with loops and lastly moving from passive gameplay to becoming the aggressor and be more active. It makes a lot of sense to have these types of excersises closer towards match-day in your schedule, for obvious reasons.
Something that cannot be stressed enough is to keep at it with a regular pace. If you truly wanna become better, you might have to force yourself to go to your club and practise whatever drill you can't stand because it works on one of your weaknesses. And in case you cannot convince your usual training partners to stick around for drills because they just wanna play a bit you shouldn't hesitate to look around at other clubs and talk to higher ranked players whether they could give you a hand. In my experience it's easier to practise with better people than yourself not only because they are better than you, but because they are motivated and want to improve their game. Duh, that's why they're so good in the first place
In conclusion I hope you got the rough idea of how you could approach your training if it is supposed to be efficient. The spark for the idea came from the german youth/cadet team, who practise in a very similar manner. However, they dedicate about as much time to Fitness and Health as to footwork, something that I skipped in the 4 months for now. That's the extra mile
