...Are you often late to appointments with others (work, meetings, medical appointments, visiting friends when a "time" is giving, etc.)? Why? If it is because you are doing other things, like checking or other OCD things, then I'd say there was a too "much" time problem.

Yes. All the 'yeah, I should do this that and the other. There's *got* to be time, because I need to do it, or can't actually leave. Or walk out door, and come back in repeatedly just to make sure. Again. And again. The option being actually leaving, but if I haven't done them, I CANNOT stop thinking about them and that something terrible will happen. More than once, this has caused me to turn around even after getting enroute. Inevitably to find that in fact the thing *is* done. Or a memorable one of waking up, going 'round and 'round that the door where I worked might not be locked -- it wasn't even a day I worked, so it wasn't even that it was me that could have forgotten it -- drove across town in my pjs just to make sure. Because I knew sleep was a lost cause if I didn't (not to mention that if I thought this and didn't do it, there would be a disaster). I didn't want to be doing it, but I had to.
The only real exception to being late is my current job. I absolutely can't afford to lose it, and being late is non-negotiable. It took a lot of effort, so to compensate, I leave super-early, yet am still completely anxious that I will get lost, even if I've gone there several/numerous times. (If a mistake is made there will be disaster because of it and I'll become super anxious should I get turned around at all, despite having Google Mapping, writing down *and* having a thorough map. Not infrequently to the point of complete meltdown where I can't think or even see straight.)

There's really no such thing as multi-tasking; one can do really fast serial tasking but you cannot attend to more than one thing at a time...

Yeah, I understand what you're saying here... it certainly is an illusion most of the time. My job absolutely requires attention to many dangerous things at once (so I am a serious swivel-head, lol) To actually focus on only one thing at a time can literally be life threatening. So though I think of it as multi-tasking (and in a sense it is), it could probably also be seen as super-rapid serial tasking.
I guess the thing I was thinking of most was more the "tapes that nearly never stop" in my mind running simultaneously with so many other activities (rarely in above case though as it takes THAT much concentration).

... so we can't "control" our thinking but we can direct it; if we think X we can decide to keep thinking about X or to go on to another thought. Sometimes it can be really hard to keep a thought in our head and keep developing that thought ...

Hard indeed. I have a lot of problem with staying on thought, my mind jumps around so badly to the point I can't remember what I just thought, no matter how "brilliant" (but that is probably something else altogether...) it seemed at that moment.

...If you are trying to go to work or bed but have to check the stove or the door locks over and over, there's a sense of frustration about doing so. If you do not have any sense of frustration in what you are doing, do not wish you were elsewhere because you are not aware, then, if you are doing things for "too long" it is probably another problem, one of awareness rather than compulsion?

... My current T nodded her head and told me that it's because I'm dissociating when I engage in the activity! Finally, someone gets it! She's exactly correct...I do dissociate when I'm engaged in the compulsive activity. I lose chunks of time. It's not like I know I'm losing time and want to stop so I can go do something else...I really have no clue how much time is passing. Usually, something happens to snap me out of the compulsive activity, and I'm often shocked at how much time has passed...
I am also a really bad judge of time. I'm rarely late for things, because I make sure to give myself double the amount of time I think I'm going to need to get somewhere, or I will use google maps to figure out how long it should take me to get somewhere. But, if someone just asks me how long it takes me to go somewhere or how long a task will take, or something, I have no concept of an accurate estimation of time...