If you are an advanced English learner, you'll benefit significantly from having the subtler aspects of your pronunciation 'tweaked' to sound the best you can. In today's competitive Globish world, it's always worth going that extra mile and stand out of the crowd.
Sadly, people will judge you on your accent. When your accent sounds fluent, but your grammar is not so great, people will think your English is excellent. However, if your grammar is amazing, but your accent is strong, people will think you can't speak English. And as unfair as it may seem, it could cost you opportunities.
Going that extra mile will require an objective and determination: You'll need a fair amount of lessons and time to do regular practice.
You have to realise that a tremendous amount of pronunciation work focuses on learning the IPA sounds, connected speech, intonation, word stress and sentence stress. Just learning the sounds individually and then learning them again in their reductions is a great feat.
There is much emphasis on distinguishing between individual sounds, minimal pairs. Such as /ʃɪp/ (ship) or /ʃi:p/ (sheep) and /tri:/ (tree) or /Ɵri:/ (three).
So, the question is, Is it important to see these differences?
The thing is, not all native speakers of English can't tell the difference (for example, many of my friends in London, native English speakers, often can be heard saying, /tri:/ (tree) instead of /Ɵri:/, (three);
If we listen to the context with which these words are mispronounced in a sentence, it will become apparent...
For example, My family sailed to Spain by/ʃi:p/: (Sheep) should have been
/ʃɪp/ (ship) It is reasonably apparent which word fits the context. Yes, that person pronounced the word 'sheep' instead of 'ship, but their message still came across.
Does this mean we shouldn’t learn and teach the IPA sounds? Not at all, but what it does say we need to think about why we need to know them.
Learning the IPA Standard English is an excellent start to modifying an accent. Tweaking just 5 or 6 vowel sounds can radically soften your accent while still maintaining your identity.
If, for example, if you are Italian, you might want to work on /æ/ and /e/ as these are often confused. Or you might wish to work on the /h/ sound as there is no equivalent in Italian, although it is crucial that learners don’t overcompensate and add an /h/ sound where there isn’t one, e.g. /haɪ/ instead of ‘I’.
I think it's important to focus on sounds that my client is struggling with; IPA is beneficial for recognition of individual sounds or whole words in the flow of speech.
I'd say the key to good pronunciation, is your intonation, if you can find the flow and melody of the English language, even if your sounds and your grammar may be off kilt. You will gain in clarity and people will still want to listen to you.
Note to yourself: An accent is what you put in speaking the new language. Having an accent is maintaining your personality while using the new language. Speaking a second language is part of our lives nowadays. As long as people understand your message, that is the most crucial part.