I can tell you how I did it. Stopwatch and webcam. Also getting used to a set of questions helped answer different questions.

I started a stopwatch and only answered the questions in my head. Went through a set of 50 questions. Noted the time. (While typing this out I think it could have been 20 questions, not sure.) I did this only three times so I had a consistent baseline.

Then I sat in front of my webcam. Put it on mirror mode so I could see my face, since faces are the most distracting to me. I should note my cam back then had a noticeable 2 second lag so that was very annoying to me. And faces are my biggest distraction. Maybe something else is in order today, since I do not know how to recreate this effect with modern software. I had the camera hooked up with FireWire and mirrored with some freeware stuff. Also my face was the wrong way further irritating me.

Different set of questions. Same number. Started the clock again. Looking down reading, then looking into the webcam when answering the question. Sound of the cam was off. First try - Took a looooong time to get through.

I only did the webcam thing the other times. I just multiplied the baseline to the cards I was reading.

If this is actually helpful to others, I don't know. Maybe you can adapt this to your needs.

On the other hand there are fast card games where you need fast hand eye coordination to pick up and throw away cards depending on the cards your opponents are playing. I never figured out how to get better there. Still bad at it.

Edited to add: I also recorded one session and I realized how slow I was speaking. it never occurred to me before, since I usually think quite fast and was usually one of the first people to finish exams.