I have often done this myself, and have seen others do it also. I hadn’t thought of it as an instruction or requirement to do so, only a way to bring the Spirit. Yet in both of these chapters, saying a prayer as a precursor to the ordinance is part of the ‘manner of’, meaning part of the expected process. In the first case, Jesus specifically instructs the brethren to do it. In the second case, it is written as one step in the process.
The practice of making time to pause and pray can be applied to anything we face. It could be for seeking guidance and assistance in completing a difficult task like taking a school exam, giving a speech, discussing a family problem, or approaching the bishop for repentance. Taking a prayerful pause can also be taken after getting through something such as any of these same examples. Taking pause can be done during a moment of pondering, or while noticing your blessings. Pausing and praying doesn’t have to be something prescribed. We don’t have to go find a place to formally kneel if it’s not available. We can just take a moment to bow our head, whisper our prayer, and collect our thoughts wherever we are. We can also consciously seek a moment of privacy where kneeling and verbal prayer are possible. In my mind, the latter is preferable.
As an example, in my recent working life I have been a speaker at meetings of a committee of the NPR Board of Directors. It was a part of my job I did almost every month. Some time just before the meeting starts I would close my office door and bow my head to ask for Heavenly Father to inspire me with the right words. I did that even though I already did as part of my normal morning prayer. I still had to do my part to be prepared for the meetings, but He helped me recall the information I needed during the presentation and in response to questions that will come up from board members.
I recommend we each take advantage of the blessing God has given us, the blessing to pause and pray with whatever life brings us. Even when we are in a hurry and have little time, taking a moment will make the outcome better.