Nobody likes to wait for things they need. Waiting can be a waste of time, and time is money. A key value of having a Designated Engineering Representative (DER) is that they can quickly answer your questions and help you avoid the waiting that will sometimes come when dealing with the FAA alone.
Consider having an FAA DER involved even in the review of proposals you are bidding on
While technically you don’t need a DER in your DO-254 process, the FAA can authorize and typically will encourage your use of FAA approved DERs in your project. You can stand in long lines (figuratively) and wait for a resource from the FAA. But the FAA has limited resources, and despite their best efforts, sometimes the wait times to get an FAA auditor are quite long. Even for projects that are not FAA certification programs or are TSOs, if you are being asked to comply with DO-254, working with an FAA authorized Airborne Electronic Hardware DER will definitely save you time, as well as provide you with advice and audit preparation, which is a very valuable facet not offered by FAA auditors. This advice and preparation can save tremendous time, effort and cost in avoided rework. Also, consider having an FAA DER involved even in the review of proposals you are bidding on. This can help you avoid costly oversights in what compliance requirements you may not be aware of in the wording and the efforts involved in satisfying these contractual requirements.
DO-254 compliance is complicated and costly. Investing a little more upfront to work with a DER can save significantly in terms of audit scheduling and makes your whole compliance experience run much more smoothly and efficiently.