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