|My take on this is if you use an abbreviation more than once on a page then first time you spell it out in full with the abbreviation in brackets, for example - Health and Safety Executive (HSE). Then thereafter I think it's perfectly acceptable to use HSE on that page without the abbr tag. However, there are instances were you might not spell it out in the context of the sentence and there I would use the abbr tag.
Completely agree with this. It's important to remember that some readers won't understand abbr and acronym tags. Screen readers will also try and pronounce an abbreviation if they think they can. The following links may also help understand how different devices behave:
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