My point is that she has a strong will and high expectations regarding the characters she plays; probably because she invest a lot of herself in playing them.
I think that she couldn't make her characters to feel so alive and real without some level of self-investment. I still hold my theory that acting is not just a job for her but also a form of self-expression . Not every person does it in the same way and somebody doesn't need to express his/herself so much but for an artist like Summer its almost a necessity. Thats the reason why she is so picky about what to play because only the roles she likes satisfy her.
Of course she needs to have strong will to get what she wants and I respect her for her strength. Anybody should I think because not everybody so strong as her as I see.