The reward for each level seems to be specific, you won't get a Talent every 2 levels.  
I'm sorry, but this is simply not true:
Max Level 20 will have:
+ 15 attribute points, + 49 skill points, + 11 talent points.
Taking "Lone Wolf" talent adds some percent of ability points.
Attr = Attribute points gained per level. Abil = Ability points gained per level. Talent = Talent points gained per level.
Level Attr  Abil Talent
 1       5     5      2  
 2       1     1      0  
 3       0     1      1  
 4       1     1      0  
 5       0     1      1  
 6       1     2      0  
 7       0     2      1  
 8       1     2      0
 9       0     2      1  
10       1     2      0  
11       0     3      1  
12       1     3      0  
13       0     3      1  
14       1     3      0  
15       0     3      1  
16       1     3      0  
17       0     3      1  
18       1     3      0  
19       0     3      1  
20       1     3      0
total   15    49     11
Source:
http://www.rpguides.de/divinity-original-sin/artikel/charakterstufen.htm