Reddit reviews Rockler 3/8'' Dowel Drilling Jig Kit

Buy this dowel jig.. Easy and inexpensive.

Are you talking about the spacing of the drill holes or the the angle in which they are drilled? Either way, use a jig to solve both.

For the spacing, I would get a 12" strip of wood, drill the hole 10" from the end, and glue a small block of wood on the end grain of one side to act like a lip. Then press that lip up against the board and use it to make sure the drill holes are consistent. That probably made no sense, but you can make something like this and have the clear part be 10" long so you have the right distance https://www.amazon.com/Rockler-Dowel-Drilling-Jig-Kit/dp/B00GBYX8C6

To make sure it is perpendicular to the face of the board, you can use a small block of wood to make this on your drill press, then just use it when you drill the actual hole. https://www.rockler.com/big-gator-v-drill-guide-metric

Use a Dowling jig