My personal preference is to teach the spelling patterns of each phoneme so that children think about how a sound can be spelt, to me this makes more sense as it is a sound to print routine.
As time passes, a phonics programme, such as Phonics International, becomes increasingly important for providing specific words for spelling. There's no way round this. Ultimately, students have to have word-specific knowledge which concerns the 'spelling alternative' for the long vowel sounds (like 'ai' or 'ay' or 'a-e' or 'a' and so on) and/or some of the consonant sounds (like 'f' or 'ff' or 'ph' or 'gh).
Phonics International works hard to provide teaching and learning resources which support the learning not only of the concepts involved (that is, different spellings for the same sound) but also for the word banks that need to be learnt for the same spelling alternatives.
Also, the ALPHABETIC CODE OVERVIEW CHARTS are, in effect, spelling reference charts based around different spelling alternatives for the same sound.
However, it's not quite as straightforward as that!
When we 'read' we need a skill that words from sound-to-print, so we need to be able to recognise letter groups. Then those letter groups may well be code for different sounds. For example, the letter group 'qu' may be /k+w/ as in 'queen' or it may be /k/ as in 'quiche'.
At first, we might learn 'qu' as /k+w/ as most words beginners encounter are 'queen', 'quick', 'quiet' and so on. But, even for reading, it helps to be looking at a bank of words.
This is an easy one for spelling, also, as there is no such grapheme as 'kw' in the English language!
However, there are some letter groups which is helpful to look at both from the spelling perspective and the reading perspective - and this might benefit from looking at some more obscure words - and when are words more obscure or not? This may be age-dependent.
For example, let's think about the grapheme 'ch'. When we see this as beginners, it's usually code for the sound /ch/ as in 'chips' and 'such'.
However, an early word is 'school' - and there are names like 'Christopher' which fit in with this code.
But also, Charlotte is a common name in some English-speaking countries -and 'ch' is now code for the sound /sh/ - which we teach as the grapheme 'sh' at first.
This could get very complicated and this is where it is helpful to have a formal, planned programme and also an 'incidental phonics teaching' approach running alongside. If you have a 'Christopher' and a 'Charlotte' in your class, you need to talk about these code variations for their benefit ahead of the introduction of this code in your programme.
The word banks for these letter groups, however, have some longer words in which may well be more appropriate for older students, such as:
chaos, orchestra, cholera, chameleon, choir, chorus
chiffon, chandelier, chalet, machine, parachute
It could be that children need to read these words in their wider reading before they can really be expected to spell these words for their writing.
The Phonics International bases most of the core SOUNDS BOOK ACTIVITY SHEETS on writing the 'grapheme' at the top of the page which is the 'new learning'. This might include, for example, a heading of y, -y, -y where the focus is on the same grapheme for different sounds. That is because there is a reading emphasis and children need to know that they will see the letter 'y' frequently and it's position in the written word will affect the pronunciation alternatives!
However, the extension SOUNDS BOOK ACTIVITY SHEETS from Unit 6 onwards are often based on the 'sound' in common to various spelling alternatives. So, there may be a heading /air/ and beneath that there will be the various spelling alternatives of 'air', '-ear', '-are' and '-ere'.
Teachers themselves need to be very clear about when they are needing to look at the teaching from the 'pronunciation alternatives' (for reading) and the 'spelling alternatives' (for spelling) and decide where the emphasis is better placed in any given exercise.
Oh boy - I hope that made sense!