Sasha and others;
I think made it up is onto something in the suggestion to spread out your l-dopa in smaller doses over time throughout the day. A practical approach that I have seen described involved dissolving sinemet tablets in a measured volume of water and sipping the resulting solution a little at a time. This might make it easier to take smaller increments of the med than trying to cut the tablets into quarter- or smaller doses.
I think the logic behind approaching the fluctuations with smaller doses spread out over time has to do with how much capacity we have left for taking up and storing dopa in our substantia nigra and striatum. As more and more neurons are lost, there is less and less "buffering capacity" in the system. What was previously handled by the remaining neurons by uptake and release becomes excessive and overwhelms the receptors.