I think it worth reading the Macaulay Library guidance in full. It is certainly excellent advice for ensuring that the recordings in the Library are of the highest standard for scientific work and the recordist does not accidentally destroy their original recording etc. Under optimum conditions this guidance is excellent. For less than optimum conditions, 'the warts and all' recording will allow people to accurately assess the value of the recording and in some cases this may be the best that anyone has achieved anyway.
If you are recording a sound track to a video you probably have other considerations, that in the time available to you, you will be recording from far from optimal conditions and the audience will be slightly more forgiving in absolute quality if you can remove the noise of screaming pre-amps and some of the wind.
Regrettably also, the Zoom H5 has good pre-amps for its price point, but not everyone else is so blessed, so the work involved in getting acceptable recordings can be that much more difficult.
So for submitting your work to libraries or even building up your own collection Scott is absolutely right( but please read the whole of what the web site has to say, it is both interesting and helpful).
For other purposes such as video work or presenting to a local gardening society, for instance, consider the audience and produce something they want to hear.
I have sat through presentations where the audience is not sure whether to laugh or cry. Its probably a good guideline that if the majority of your presentation is not fit for human consumption, don't present it, but 'tweaking' a recording so it sounds nice over a village hall p.a. system is pure courtesy to your audience and you have the unedited originals available for other uses anyway.
Your audio expertise gets better the more you do, and you will only learn from experimentation. However, where guidelines exist for particular uses - do what Scott says - follow them, and in all other cases consider the needs of your audience - even if it is just you! There are also some excellent books on general audio recording, if you want to understand the theory a bit better, but they can be heavy going.
I can endorse the Zoom H5 with the SGH-6 he uses, its one of the set-ups I use from time to time, I havn't tried the SHH-6 which is the strereo version and clearly has its uses. The H4N Pro which is where this thread started has the same excellent pre-amps as the H5, but without the replaceable mic capsules.
