Phonics is useful for learning to spell words which follow the main English spelling patterns, such as 'cat, hat, sat' or 'date, late, mate', but not the 4,000 common words which disobey them in some way (plait, wait, eight, straight ...). The tricky or variant letters in them all have to be learned word by word.
For some sounds English does not even have a clearly dominant spelling pattern:
put foot would
speak speech shriek seize machine
shoddy body, copy poppy, muddy study, arrive arise
(i.e. consonant doubling in longer words is completely random).
The need to memorise the spellings of so many words one by one makes learning to write English very time-consuming (10 years, against just 1 year for Finnish). It also causes far more literacy testing, but nearly half of all school leavers never become proficient spellers.
Learning to spell English correctly (rather than phonically or sensibly) is mainly a matter of imprinting the right look of words on your mind. Apart from lots of writing, and the old LOOK - SAY - COVER - WRITE -CHECK method for words which won't stick, reading is what helps with learning to spell most of all.
Masha Bell