It's been a recurring theme of this site that the irregularities in English spelling make it harder for people to learn to read. Most of the time, this is seen as a problem for low-attaining children and those who don't have support from home, but it also affects children who have had full parental support.
Our latest example is a a bright seven year old, who had problems with phonics and read the as ten. Her father said she could not make sense of th, and this is not surprising, as it is an invention of Norman scribes to replace Anglo-saxon letters that reflected the sound more consistently. An explanation that her thinking was more consistent than that behind the spelling system, and a little practice, had her reading the, this, that and then without problems in a couple of minutes. The point about consistency in thinking is a matter of fact - Norman French introduced a different system of logic into English spelling, and this needs to be explained and taught. Explaining it in terms of "unusual phoneme-grapheme correspondence" does not help, as this does not explain why the correspondence is unusual. All it does is dress it up in terminology that makes no sense to young children and is an obstacle to understanding even for adults. Explaining the historical development usually solves the problem.
Some children, as we know from brain research, are slower to make connections between sounds and symbols, leading some people to conclude that phonics don't work for them. This is also an error, as there is no way of reading an alphabetic script without using the information that is contained in letters. The solution is to help the child build up an understanding of sound-letter correspondences by reinforcing each one, as it occurs, with similar examples, usually focusing on the final ( sometimes called rime) part. This is accurately described, following Goswami's research, as "learning by analogy". Phonics is learning by analogy too - it's just that the analogies are more consistent in phonically regular words. But we don't grind. We think, note, study and learn. Then speed recognition work to make it more automatic, combined with reading interesting stories that make us read words in context.
Finally, all children need to work at the level of their intellectual understanding while tackling their problems with basic reading, or they become bored. In the case of this seven year old, the interest was in science, and we discussed the physics of hot air balloons, the difference between airships (dirigibles) and balloons, disasters (catastrophes) and the differences between hydrogen and helium, both of which words were easy for her to read, as they stick in the memory (a well-known phenomenon, which has contributed to the error of look and say in reading teaching, as some long and complicated words will stick in the mind, whether or not they have been read using letters. The generalisation of this phenomenon to try to deal with large numbers of words that do not have unusual shapes, has been a big contributor to reading failure.)
So, the problem, and the solution. Nothing less than a full understanding of the issues will do, and too few people concerned with the work have it. Result, to quote Mr Micawber -"misery".