On wedged half dove tailed through tenons I have draw bored in two direction, sucking the joint to the shoulder and down to the dovetail. I think this assist with the drying issue and helps with keeping the weight off the peg after it is dried. Have I been seeing this correctly?

The 5" peg spacing makes sense to me. If 5" is the max distance apart what is the limit in how close they could be? I see the size of the tenon having much to do with this. You only have so much space on an 8" wide tenon.

I read of late here on this topic in a link where "they" don't want pegs larger than 1-1/4", there was not an explanation but unless it was a very large tenon it would be removing a lot of wood and the relish would be the weak link, I believe there is a happy medium.

I have used half a 2" peg, that is split down the length, on an extended through tenon acting as a wedge under the tie on a king post. Still trying to figure out if it was a peg, pin, or a wedge? For that matter are all peg/pins wedges if they are draw bored?

Tim