Learn English – “You should be well-organised” or “You should be well organised”

"Place your feet apart by a shoulder width" means to literally place your feet apart by the width of one shoulder. This does not seem to be the intention, and as such it is incorrect.

When you hyphenate, you combine the terms into a new adjective with a new, possibly idiomatic meaning, that is the width from the left shoulder to the right shoulder in a person.

It should also be noted 'shoulders-width' is also a common usage of this term.

As you have already found, there seems to be discrepancies from various sources on how to hyphenate "standardize." The main problem is that there is no universal standard on how to hyphenate words, at least in English (can't speak for other languages). Depending on the dictionary or style manual you are using, each could give a different hyphenation variation for the same word.

Syllables

Syllabification is one of, but not the only thing, that can determine the hyphenation of a word in English. Syllabification is determined by the pronunciation of the word, not the spelling, so the pronunciation used is one factor that can alter the hyphenation of a word.

To determine the syllabification of standardize, I am going to use the American English pronunciation as an example:

stændəɹdɑɪz

The first step is to determine which are the consonant phonemes and which are the vowels and vowel-like phonemes, which in this case resolves to:

s | t | æ | n | d | ə | ɹ | d | ɑɪ | z
C | C | V | C | C | V | C | C | V  | C

A syllable can have three parts, the onset, the nucleus, and the coda. The nucleus is made up of the vowel or vowel-like sounds and is a required part of the syllable. The onset is the consonants that prefix the nucleus, and the coda is the consonants that come after.

There are several phonological rules (sonority sequencing principle, phonotactic constraints) that control how to divide consonants between nuclei, but most of them are irrelevant to this question. What we are interested is the maximum onset principle. Without the maximum onset principle, we can determine the syllabification so far as follows:

s | t | æ | n | d | ə | ɹ | d | ɑɪ | z
C | C | V | C | C | V | C | C | V  | C
1 | 1 | 1 | 1 | ? | 2 | 2 | ? | 3  | 3

In this case, both d's in standardize are intervocalic consonants, which often sound as if they could be part of either the preceding syllable or the subsequent one. The maximum onset principle states that when the syllabification of intervocalic consonants are in question, the consonant should be assigned to the subsequent syllable, in order to give the syllable the maximum onset possible, i.e. if the d in standard was assigned to the first syllable, as in stand-ard, the second syllable would not have an onset at all, so the d should be assigned to the second.

Following these rules, standardize should be hyphenated as stan-dar-dize.

Etymology

However! English hyphenation does not only take pronunciation into account, it also takes into account etymology. Standardize can be divided into a root word (standard) and suffix (ize), putting the hyphenation divider between standard and ize instead of standar and dize.

Conclusion

Taking both etymology and pronunciation into account, as I believe most would do in the case of determine hyphenation for line breaks, I would personally lean toward standardize being divided as

stan-dard-ize

This takes into account pronunciation for the dividing line between the first two syllables and etymology to divide the second and last.

From a purely pronunciation perspective (and as should be listed in a dictionary), I would break it up as:

stan-dar-dize

Still, as I said, there is nothing governing or enforcing these rules especially in regards to when etymology trumps phonological syllabification, hence the variations you see.

Other Links:

1. LingPipe: Hyphenation and Syllabification Tutorial
2. IPA pronunciation of standardize from Cambridge Dictionary Online
3. Anatomy of a Syllable