I'm not sure how to answer this as for me it's a yes, and a no. I'm not ever late to appts. As a matter of fact, being late for stuff, and things not going according to the predetermined plan in my head is probably 2nd on my list of things that cause meltdowns.
However, one appt. can take me all day to plan, and prepare for. I am much, much slower at getting things done than others. I think this has to do with multitasking. My husband once commented that I get everything done everyday that needs to be done, but it takes me all day to do it, where as it would take most people a few hours to do the same tasks, because I don't multitask.
Not being able to judge the amount of time that has passed, from what I've read, is an NLD trait. Amazingly, one of the very few that I don't seem to possess. I've noticed that dyslexics also have trouble with this, but in a different way. They'll get the info all mixed up, and show up on the 8th at 10:00 (for example) when the appt was the 10th at 8:00. Or, if I tell my husband to be here at a quarter to 9, he'll show up at a quarter after 9. He also can't seem to judge how long things will take, and is late constantly because he tried to fit 2 hours worth of errands, and tasks into a one hour time frame. He never remembers to calculate time for driving, waiting in line, ect..