I also think the contents are not evenly distributed. But considering how the drug works (take a while to the concentration to go up/down), I decided to: cut a 5mg pill in 4 (or 5) as even as possible, but then, storing the pieces in a single vial/pot. So, if I split 2 pills, I use 2 plastic containers: 1 for each "pill".
Then, I use one container at a time. This way, at least I know I ingested 5mg in 4 or 5 days.
On the other hand, if you cut all your pills and store all the pieces in a single container, then you could very well ingest all the "high-concentration" pieces first, and have more than 5mg / 5 days.
Make sense??