Dunno, but all i know is that there can be a big difference in how many numbers you remove in a given range.

I had a couple of times that no nimber was removed in over 6G, but the closest numbers removed had a prime factor less then 4M away.

This is the breakdown of numbers removed in a 10G range (starting with 210-220G)

2-6-4-8-6-4-5-3-9

As you can see, a big difference.

And the higher you sieve, the less candidates you remove