Interesting one this. Tends to always arouse vocally strong opinions by those who have one on this subject.
I would humbly suggest that the ‘correct’ answer is to run 5k at a constant speed, which of course is difficult. But with the wonders of modern pacing technologies it is quite possible for an average runner. I would support my answer with the evidence that world records over middle distances tend to have an even split ie the first half is as fast as the second with the focus being on constant speed.
Having said that I always get a bit carried away at the start, run at the correct speed for the next 2k. Then my lack of stamina hits home and my 4th K suffers but with the finish line in sight I sprint a blistering final K. Which of course implies that I was not trying hard enough for the previous 4k. Perfect! Not.
I think though that we are all imperfect. If certain things work for you stick to them. However I would suggest that too strong a first k or first 2k would seriously impede your subsequent performance. Having said that my all time PB comes from running the first mile too fast.