In some of the past replies, we can see that 'Chrysler' (whatever that is) has two very different and conflicting responses.
If in fact the oil doesn't like to turn the corner to #4, then anything you do to aid that situation would be helpful. In this case, smoothing the entry of the passage to the galley would do just that. So on one hand the oil doesn't want to make a sharp turn and on the other hand it also doesn't respond to a less-sharp turn. Nonsensical.
The kernel of truth in all that is simple - the oil doesn't mind making a turn because it has to - it's under a lot of pressure. More, as YR noted, the size of the passage is in excess of the size needed to satisfy the bearing leakage rate. So, the oil isn't really seeing a high flow 'shear' situation when it turns....it's just going where it's forced to go. Looking at it another way, the passage is 1/4" diameter and the oil is freely turning and flowing down the imaginary 1/8 passage that exists right down the center of the 1/4" passage. There's even a nice gentle radius there, you just can't see it.
That said, if the 1/4" passage is plenty big enough...why are we enlarging them to 5/16? Just to be damn sure?