Here is a pretty simple idea that may be worth testing a bit to see how it goes.

I will give a quick example using the sixlines and the quads.

Sixlines...

1-6
7-12
13-18
19-24
25-30
31-36

Quads...

1-9
10-18
19-27
28-36

I got the following numbers from Spielbank Wiesbaden.

24
13
31
19
27
29
24
4
18
29
30
14
22
29
17

I will convert the above numbers to the Quads first.

3
2
4
3
3
4
3
1
2
4
4
2
3
4
2

Now it's pretty simple. All you do is look for the most recent two of the same and bet for that until there is a change and you have a new most recent two.

So here is how it would go for the Quads.

3
2
4
3 **The 3 here is the most recent two**
3  win (+3)
4  loss (+2)
3  win (+5)
1  loss (+4)
2  loss (+3)
4  loss (+2)  **The 4 is now the most recent two**
4  win (+5)
2  loss (+4)
3  loss (+3)
4  win (+6)
2  loss (+5)  **The 2 is now the most recent two**


Now here are the numbers converted to the Sixlines.

4
3
6
4
5
5
4
1
3
5
5
3
4
5
3

Here is how it would go for the Sixlines.

4
3
6
4 **The 4 is the most recent two**
5  loss (-1)
5  loss (-2)  **The 5 is the most recent two**
4  loss (-3)
1  loss (-4)
3  loss (-5)
5  win (level)
5  win (+5)
3  loss (+4) 
4  loss (+3)
5  win (+8)
3  loss (+7)  **The 3 is the most recent two**

That's it basically.

I was thinking about progressions for this.

For the Quads...

Maybe something like 111 222 333

For the Sixlines...

1111 2222 3333

or something along those lines.

cheers