Jeff,
For Non Catalog PR above a dollar amount threshold, we require the requester to select their assigned buyer. In certain commodities where we have centralized buying (IT, EH&S) we automatically assign the buyer to the PR. The buyer gets painted into the PR approval flow first and last after any required business (finance) approvals. This gives the buyer a chance to adjust the PR before business approval and make any sourcing, supplier or price adjustments to save time at the end of the approval process. If the buyer is going to be out of the office for a period of time, the buyer delegates his approval to an alternate buyer. This saves PR's from being delayed.