Agreed for a technician-, basic coder or clerical-level position, but at the developer, engineer or similar professional-level position it is a reasonable expectation for the employee to work on tasks that can't be clearly defined in advanced, that don't have checklists (creating one may be a deliverable of the professional), and surprise or firefighting type situations that the techs and clericals can't resolve with the pre-existing check lists. Granted it is possible to reduce surprises with basic workplace stuff like meeting agendas and advance notice of policies, but one the flip side dealing with urgent, unplanned issues is an important part of most jobs.
It's a difficult road to navigate. I'll add a suggestion from the other side, as someone who has managed people with this style of accommodations due to ASD-type conditions. Be as open and willing to collaborate with your supervisor as possible; help educate them. If you only work through an HR person to specify your ADA or other workplace accommodations, there is an extremely limited amount of information they can legally share with your supervisor. Of course it is your legal right to keep these things private if you choose, but it makes it much harder for your supervisor to meet your needs and to foster a productive work environment for you. It does require some trust, but the outcome can be much better. I've had it go both ways.