Once again I stick to flat betting and a grid. Line 1-6: 1-6. Line 2: 7-12. Etc.
When only four numbers out of six have come, there are 15 possible combinations. Probably the four numbers do not form two groups.  Only three combinations form two groups. For example 1&2 and 4&5. 1&2 and 5&6. 2&3 and 5&6. Nevertheless I  bet that four numbers form two such groups (flat betting). 
In the grid we have six horizontal and six vertical group. 3/15 X 12 = 2,4.  In average we should expect  to see the pattern 2,4 times. 2,4 hits
I end the session at the latest  when only seven numbers have not come.

For each session we need a grid (6x6). The first line contains 1-6. The second line consists of 7-12. Etc.
There are six horizontal and six vertical groups.  When I am winning, some number has just UNITED an isolated number with a group of numbers. I try to keep it simple. An example from the first line: 2, 4 and 5 came.  I then bet that 3 comes and unites the isolated 2 with 4&5. If 1 comes first, 2 is not isolated there anymore and must be abandoned.
The session ends, if only seven of the 36 numbers are missing.

We do not have to support magical thinking, complicated thinking, technicalities, or advanced courses. Let us simply place area 1-36 in a square or grid (6x6). I am not a numerologist, so there´s nothing magical in there. The 1st horizontal line is simply with 1, 2, 3, 4, 5, and 6.  ETC. I have earlier spelled this out in vls roulette forum.
Most of us probably know, that SIX numbers may fail to come for at long time. So it might not be smart  to bet, that all six numbers in any horizontal or vertical group are bound to come soon. THE APPEARANCE  OF AT LEAST FIVE NUMBERS IN A ROW IN ONE OF THESE GROUPS SEEMS TO BE A BETTER GOAL.  When I reach this simple goal, I win (Straight Up) and end the session.

One session per day in my free test at home with pen and paper. As usual I begin with the first spin from 2011, table 3, Spielbank Wiesbaden.
The 31 sessions of January 2011 resulted in 334 chips. The first four months of 2011 (119 sessions) resulted in 389 chips.
I hope that some of you are willing to do more tests. Thanks.

X =  Winning number. 0 = Missing number.  I hope that the pattern comes somewhere in one of the three columns. If it does, I´ll win (flat betting Straight Up) and end the session. An example of the final pattern: 3    9   15 in the 3rd column. Please note that  6 and 12 are missing! My purpose of including missing numbers in the pattern is to create a rather limited bet selection. The betting should be limited in time too. So the session also ends, of any street or any carré (square or corner) in area 1-36 has come with all of its numbers.
I have been working hard trying to improve the session. With some luck I have added double streets (six lines) to my betting  in this simple way: When only one of the two groups in a dozen has come, I am betting the other one. I.e. IF  7-12 has come, I am placing one chip at a time on  1-6.
                                                                                             IF 13-18   -    -   ,  I  -      -       -     -    - -    -   -  19-24.
                                                                                             If 31-36    -    -  ,   I  -     -       -     -    -  -    -   -  25-30.

But of course we should avoid these groups, if we are Straight Up purists.