What usually happens is this: Someone decides they'd like dreadlocks, they get excited about dreadlocks, they do a little research about dreadlocks and learn how to make them, they create one test dreadlock just to see whether it works... then they create another and another and before they know it, they've got a whole head! Creating dreadlocks is fun and addictive, so once you've started, it's hard to stop. The problem that then arises is that spontaneous dreadlocks are rarely ever sectioned. Sectioning is boring and creating dreadlocks is fun... so.
Anyway, after a little time the differences between sectioned and unsectioned dreadlocks start to become apparent, leading the people with unsectioned dreadlocks to worry and wonder whether they've done the right thing. So I'm going to go through the main differences between sectioned and unsectioned dreadlocks.
First a quick introduction to sectioning for those who don't know what I'm talking about. Sectioning is when you well.. section off the hair into... sections for creating dreadlocks. What this basically means is you carve up the scalp into (usually) squares and these squares of hair are what go on to form the dreadlock, they become the root of the dreadlock you're forming. Sectioning can either be done one at a time - create a square section, create a dreadlock, repeat. Or all at once by creating a whole head of sections, held with elastic bands and then going back to create the dreadlocks.
So what are the benefits of sectioning? Sectioning allows you to decide where the roots are going to go and therefore decide where the dreadlocks are going to go - you can position the dreadlocks wherever you like. You can also decide how large the sections are going to be and therefore you have some control over the thickness of the dreadlocks. If you do not section, you do not have quite as much control - you still have more control than you would with the natural/neglect/freeform method, because of course you still choose which lumps of hair you're going to create the dreadlocks from, but it's not as accurate as having sectioned first. Some people might prefer the more randomised nature of non-sectioned dreadlocks.
The main problem with not sectioning is that the young dreadlocks are far more prone to congoing/fusing/merging together. When you section the hair you scoop up all the hairs that grow in one particular section and form them into a dreadlock. A perfectly sectioned head would have every single hair neatly stored away in it's correct section - which would be underneath the dreadlock that it should grow into. If you don't section you can end up with very strange sized roots that can overlap. One dreadlock might be pulling in hairs that really should be growing into it's neighbour dreadlock. There can also be little patches of hair that have not been included into a dreadlock at all! All these non-sectioned roots can greatly increase the chance that the dreadlocks will start to stick together at the roots. Now let me say that sectioning, even perfect sectioning is by no means a guarantee that the dreadlocks won't stick together, but it really, really helps.
So if you have unsectioned dreadlocks, is it recommended to take them out and start over sectioned? I would recommend starting over if you are unhappy with the size or positioning of the dreadlock or if you have a low pain threshold (I'll come back to that). Dreadlocks take a long time to start and to then spend all the time required to take them out, section and restart is only worth it if you are unhappy with the fundamental layout of the dreadlocks. Having unsectioned dreadlocks will mean that more separating is required, now this involves taking dreadlocks and pulling them in opposite directions to stop them sticking together - this can be quite painful. Once you've separated them enough you'll have split the dreadlocks right down to the roots and they'll grow the same as sectioned dreadlocks - so it really comes down to how much extra separating you can really deal with.
My recommendation is to section whenever possible. Any measures that can reduce the amount of separating you have to do to young dreadlocks is a bonus in my book. There are no rules that state you have to make the sections neat and uniform, you can make them as different as you like to still achieve a random, disorganised look, but while still saving yourself some of the stress involved from unsectioned dreadlocks.