Amount of Uke-Ire Tiles for Ko-Ritsu-Hai (The Basics pt05)

Check Mahjong No Jan-Ryu for the original article. 

*Translation of the original article start below*

"Depending on the tiles, the amount of Uke-Ire (effective draw) tiles will vary"

Tiles that are relavent to what you have have are called "Uke-Ire" (effective draws) or "Kuttsuki" (connecting) , but depending on the "Ko-Ritsu-Hai" (Isolated Tiles), the amount of Uke-Ire (Kuttsuki)  tiles will vary.  

In case of 3, and you draw a 2 or 4, we express this as "The tiles come next to it". If you have Ton/East and you draw another Ton/East, we express this as "The tiles comes on top of it".  As you can see below, and you consider the Uke-Ire, it is obvious that the tiles are easier to connect next to a tile rather than on top.  

[In the Case of Ji-Hai] Uke-Ire Tiles are 1 Type, 3 Tiles
Ton/East -> Draw Ton/East and it only becomes 2 Ton/East.

[In the Case of 1 or 9] Uke-Ire Tiles are 3 Types, 11 Tiles
(No Riyan-Men Wait, but there are 3 Patterns)
1P -> Draw 1P and becomes 2 1Ps
-> Draw 2P and becomes 1P2P
-> Draw 3P and becomes 1P3P

[In the Case of 2 or 8] Uke-Ire Tiles are 4 Types, 15 Tiles
(4 Patterns. 1 Type, 4 Tiles and a Riyan-Men is even possible!)
2P -> Draw 1P and becomes 1P2P
-> Draw 2P and becomes 2P2P
-> Draw 3P and becomes 2P3P
-> Draw 4P and becomes 2P4P

Keep in mind that there is a big difference between "1" and "2". 

"3~7 tiles will have much wider Uke-Ire"

And when it comes to "3" "4" "5" "6" and "7", the Uke-Ire tiles becomes even more significant. 

[In the case of 3~7] 5 Types and 19 Tiles
(5 Patterns. 2 Type, 8 Tiles and a Riyan-Men is even possible!)
5P -> Draw 3P and becomes 3P5P
-> Draw 4P and becomes 4P5P
-> Draw 5P and becomes 5P5P
-> Draw 6P and becomes 5P6P
-> Draw 7P and becomes 5P7P

Let's try and understand the amount of Uke-Ire tiles differences in these cases. If you put more value in the "3~7" Ko-Ritsu-Hai's, you will become one step closer to winning. 

If you plan to discards 1 tile with this hand....
You would basically discard the 9P since it has the least amount of Uke-Ire tiles.

Let's remember that the Uke-Ire Tile amounts order of priority is【 ①3~7 ＞ ②2 or 8 ＞ ③1 or 9＞ ④Ji-Hai 】