Although children learning to read using the Speech Sound Pics (SSP) Approach can recognise and blend the phoneme to grapheme correspondences taught systematically throughout the 4 Code Levels, they ALSO explore the whole code (at least 350 correspondences as seen in the Spelling Clouds)
Even pre-schoolers can then use this code knowledge to figure out unfamiliar words and their likely pronunciation options- even if not a real word (as tested in the PSC) They understand so much about the code! 
To develop orthographic mapping skills students need to explore the whole code - and most learning (in a speech to print phonics learning environment) is implicit. The aim is to guide students towards 'self-teaching' as quickly as possible, using the foundation of explicit phonics instruction.
Much more is needed to read of course, but the Spelling Clouds are a great way to explore spelling choices at any age.