johnt said: "Why is the norm not to take more frequent, but smaller doses?"

One answer to this question is that taking more frequent but smaller doses might be considered by some to be too onerous, both in terms of the larger number of doses, and the increased difficulty of timing the doses in relation to food intake.

Here is the story behind my answer, for those with time to spare.

About a year ago my neuro thought my tremor could be improved by increasing my dosage of Madopar 125 from 3 tablets per day to 4.5 tablets per day. When I tried the new dosage I experienced dystonic dyskinesia in my right foot (it started about half an hour after I took the new dose, and lasted for about one hour). I reduced the dosage back to 3 tablets per day but the dyskinesia still occurred. I phoned the Parkinson's nurse for advice and she said it was up to me to choose the dosage, based of whether it was the tremor or the dyskinesia which bothered me the most. I asked her whether it was worth me trying a dosage of half a tablet 6 times a day, and she said "Too onerous!" But I did it anyway, and the dyskinesia stopped occurring. About 6 months ago (after my last visit to the neuro) we increased the dosage to three quarters of a tablet 6 times a day, and the dyskinesia has not re-occurred.

Taking a dose 6 times per day may seem bothersome, but so far it has been a breeze. We've set up an alarm on the screen-phone to go off at 2.5 hour intervals starting at 8am. When I am out and about I wear a bum bag containing a small bottle of water and some half tablets and quarter tablets. I'm also lucky in that, at this early stage (diagnosed June 2015), when I eat doesn't seem to have any noticeable effect on the medication. I can also miss a dose by half an hour (or even one hour) and, at this stage, this also seems to have no noticeable effect.