The sales interview process has steps and somewhat of an expectation of things you will need to do and bring before getting a job offer. For example, you will most likely have a phone interview or two, followed by a face to face interview or two and a final interview with the hiring manager's boss. In these interviews, it is common practice to bring a resume, a brag book as well as a 30/60/90 day plan. I coach sales candidates to understand the sales interview process and to make sure to provide the documents and items that the hiring sales managers will expect to see during the sales interview process.
The one good reason for having a 30/60/90 day sales plan is that you will not eliminate yourself from the selection process by not having one. Imagine if the sales job came down between you and another candidate, and the deciding factor might just be that one thing that the other sales candidate did and you didn't. Know the sales interview process and know the specific sales interview process for the company you are interviewing for. You can simply find this out by asking. I had a sales Director who interviews my final sales candidates and made a comment to me once when a sales candidate didn't bring in a 30/60/90 day plan, "the candidate didn't bring in a 30/60/90 day plan, that is a red flag." I then mentioned to him that he never even looks at those, but his response to this was that, "yes, but it is expected to show how serious you are and if you put in the effort to get the sales job." It is a better choice to cover all your bases versus leaving your hiring to chance.
You also want to give yourself the best chance possible if you are going to pursue a sales job. It takes a lot of time to prepare and to interview, so you might as well set yourself up to succeed. Think of it this way, you are the product and the 30/60/90 day plan is your 90 day plan to prove that you know what to do and have thought it through on how to get up to speed as soon as possible. It is your marketing piece and proof source that you are right person for the job.
Learn how to create your own 30/60/90 day plan!