I was a Customer Success Manager for the best sales rep in our company. He has been there for years and had deep relationships with all 60 of his accounts (deep as in went fishing with, knew their families).
Side note: he hand-wrote all of his notes and his home office had filing cabinets FILLED with information about where accounts stood, things coming up, what each account was interested in.
He found a better job and let the company know and said since he has a good relationship with his accounts and it's the right thing to do he is giving them 30 days and within that time he will introduce the appropriate rep to his accounts to have a smooth transition. His direct boss was grateful that he would do that instead of leaving them high and dry. When his boss told their boss they canned him that day. They thought since I was his inside counterpart, I would have all the information (without asking me).
He called me and let me know that they let him go and didn't need him to help introduce the reps to his accounts. He shred everything the next day.
Two days later I get called into a meeting with a few reps and the VP of sales. They said “as you know 'X' was let go and we just need you to give us a run down of all of his accounts since there was minimal notes put into the CRM” I told them that he had everything at his home office in filing cabinets and didn't let me in on everything going on that I wasn't apart of because he was so busy and I was handling things that were in the pipe, but nothing more.
When I tell you the place went into a frenzy, it was wild.
The VP stormed out, the reps were told that they (the company) had all the information already (thinking I had everything without asking me). Within the next few months, half of his accounts went silent and discontinued service.
He told me when I first started working with him that the company doesn't care about you and you shouldn't let them see your hand, if you show everything, they can walk all over you. I absolutely believe this now.