Hey ... I am a salesperson and definitely believe that commissions are paid in perpetuity. There is no way that one can maintain and grow a book of business by bringing in the client and walking away from it. The salesperson has to stay entrenched ... but booking the trucks, micromanaging etc ... for the most part no. I think in produce it is necessary though.
A salesperson's job is to keep abreast of how the industry is doing and what it means for the relationship between the company and its clients (who by and large do move with the salespeople, albeit not always immediately). The salesperson then tailors the solutions around this.
When a salesperson is established with a solid book, a good salesperson will not stop calling on new business but will be more selective of which business he/she pursues. It's as much a benefit for the employer than him/herself.
As far as being reachable, I can tell you that I am ALWAYS reachable, not just M-F 8-5 ... that's what a Blackberry is for. A good salesperson NEVER closes for business. But we don't chain ourselves to our desks either. The only time I don't answer is when I am in a situation where it is inappropriate for me to do so (ie when I am with a customer). When you are with a customer, regardless of in person, on the phone, or in email, that customer deserves your full attention at the time -- not divided between other parties. Customers need to feel important.
I'm not saying that there are not lazy salespeople out there who bring it and leave it ... or are unreachable, that sort of thing. I'd say the majority do ... but this is what seperates the sales leaders from the mediocre ones. I'd say in all honesty that 80% of those who call themselves salespeople, no matter what the industry, can be like this, and it shows in their paychecks ultimately.