As stated in OP it stretches to roughly 1500pp which roughly equals the ability to play any map up to 3.5 stars that isn't poorly mapped or very special. It's just an estimate from me though. I still use this system.
When moving on to easy and medium insanes you'll get very different results depending on how much the map caters your skillset - this already applies to easier maps but the further you move the greater the difference becomes. As you can see from my topplays I have some 99%+ FCs on maps that are 4,5-4,95 stars but this is due to the map catering my skillset very well:
They are relatively aimheavy, not very fast, easy to read and possess no longer streams(more than 8 notes) and on some of them triples even tend to end on a slider which makes them easier to get 300s on.
This is a combination that a lot of players are good at which why some of these maps are also considered "farm-maps" to get some easy pp.
And then there are maps like this:
https://osu.ppy.sh/b/119582This map has a tricky rhythm and you need good reading to see if the stacked notes are 1/2 or 1/4. As it's also kind of fast you don't have time to think and it is hard to get good accuracy on it. I have to give a serious effort to gain about 95% and I'm not consistent enough to FC it even though it has only 3,78 stars. And in this example the map is not bad, it's me who is bad.
There are other maps around 3.5-4 stars that are too hard for me to either FC or get good accuracy on.
Now the lame thing is that if I keep sightreading maps from 3.5-4 stars I get bored cause any map that follows the aimheavy+easy to read pattern is relatively easy and I can get a lot of good plays into my higher brackets without finding a map that is suited for practice due to this kind of map being dominant.
This is obviously boring and as a result I prefer sightreading stuff from 3.8 stars up to 5 stars(and let other ppl give me hard maps at low star diff).
As a result the star diff of the maps I practice by brackets and the star diff of maps I sightread diverges and most maps that turn out to be good practice on sightread are maps that I have to play with NF AND due to the difficulty sort I won't even play them for a long time due to lower star maps "blocking" me.
Theoretically you're right. Of course this system should keep being useful if one really focuses on getting an allround-skillset but my intention was to give new players a practice system that will give them a grasp of the basic things they need to enjoy the game for a long time:
Being able to play smooth triples, medium jumps, read some non-obvious patterns and maintain good accuracy overall(if they want to).
It's up to everyone where he wants to go with his gameplay but these things will help you out on every map.
The ability to SS
this map is nice and dandy but there's no need for it to enjoy the game for a very long time regardless of your motivation to play.
