I would think it would help with evaluation. You can't rely on memorization with opening theory as each game has a different start position. This will force you to think more before each move. Looking at the board to know where your pieces and your opponents pieces are placed. How it would be best to push your pawns and develop pieces. What are the advantages and disadvantages.
It should help if you're playing longer time controls and analyzing your games. As it would be if you did the same for standard chess. How many games you should play depends on how it affects the quality of your games. Whether you have enough time for each game and to analyze those games. As for the correct ratio of games, it would depend on playing enough of both to see improvements.


I've been trying to work on my ability to evaluate positions and I'm thinking that perhaps 960 is a good try at this especially at my level. By ensuring different imbalances from the very beginning of the game I feel that the training in this aspect starts from the very beginning and that the end analysis might be even more instructive. Perhaps this targets evaluation more than classic chess.
I think exercises (say # games/week) with this would be beneficial in certain aspects of the game and by no means believe that it can improve your game without the correct number of classic chess games to compliment it.
Of course the numbers of how many games is healthy for one's chess seems to be very subjective.
What are your thoughts on this matter?