Because Britney Spears has proven over the years that she makes an exceptional mother, she now has the kids more than 50% of the time. Given Kevin Federline as the alternative, this isn't as horrible as it seems for the kids. TMZ says:
Contrary to some reports, we know that before the change Britney had the kids 50% of the time.
The 50/50 split will go back into effect once Britney's tour is over.
Not sure I understand why she would get the kids over 50% of the time while on tour, but then again, I haven't understood a decision involving Britney Spears for at least 10 years. But anyway, here she is on a yacht recently.