One principle governing the use of phonetic symbols is that there should be one symbol for every sound, the number of letters in ordinary spelling is simply irrelevant.
Answers
“One Sound, One Symbol” is the principle governing the use of phonetic symbols whereas, the number of letters in a word may vary. For example epitaph – has the pronunciation of “f” sound in the last. In writing, strictly following phonetic sound will lead to distortion of a message. We would need more than 40 different phonemic symbols to represent each character in a spelling.
The person who is writing a message would write only once but, it will be read more than once. So, the writing has to be clear. “As Trask says, “English spelling is notoriously complex, irregular and eccentric, more so than in almost any other written language on earth”. So, compromises have to be made with regard to spelling and the rules too have to be changed. This is an ongoing process and it cannot be implemented over-night.