Colourist told me my inspo pic would take THREE sessions and £500. Second salon said one session, no problem. Who's telling me the truth?

Box dye brunette (I know, I know) wanting to get to a cool toned bronde/light brown. Went for two consultations because I wanted to compare.

Salon A: colourist did a strand test, took ages looking at my roots vs lengths, said realistically three sessions spaced 6-8 weeks apart, roughly £500 all in, and even then she couldn't promise the exact photo because of the box dye build up on my ends. Was very calm about it, wasn't trying to sell me anything, actually said "or you could grow it out and we do it properly next year".

Salon B: looked at the photo for about ten seconds, said "yeah no problem, one session, £180", didn't touch my hair, didn't ask what I'd used on it.

So obviously salon B is £320 cheaper and four months faster. And obviously that's exactly why I don't trust it??

But then part of me thinks maybe Salon A is being overly cautious to build in a safety net, or upselling me into three appointments when one would do. I genuinely don't know enough to judge.

Colourists — is three sessions from box dye brunette to bronde realistic or is that excessive? And is there a question I can ask salon B that would tell me whether she actually knows what she's doing or is just saying yes to get the booking?

Really don't want to be the person posting a photo of orange hair in here next week.