Any Hairdressers / Cosmetologists here?

Hi, so I just have a question. I dyed my hair dark brown in August from my natural dark blonde and have had it touched up once since then, at the end of September or first of October. I regretted it before the touch up but my hair dresser didn't have time to do much else to my hair because I didn't tell them what I wanted done during my appointment. So anyway, I had super blonde hair this spring and I want to go back to that. My hair dresser says it would have to happen gradually. I was just wondering, is that really necessary? I know going super light can damage your hair but isn't it going to do that regardless of how gradual? My issue is that my hair dresser is in my hometown and I currently live 3 hours away but see her when we go home and she has openings, but she hardly ever does on Saturdays when I'm in. So I have to find someone new in my current city and I need to know if I can just have a new one do it all at once or if I need to make sure they do it gradually. Here is my natural hair color, my hair now and then the color I'd like to get to: