Rav Chaim Kanievsky famously has been shortening the standard bracha he gives to the many thousands of visitors from the full "bracha vehatzlacha" - blessings and success", to "BUAH" - an abbreviation for bracha vehatzlacha. It was explained to me by someone who goes to him regularly that he is so busy learning, he does whatever he can to minimize any time away from learning. With so many people visiting him and requesting a bracha, he decided the bracha vehatzlacha bracha, as minimal as it already is, could be shortened to its abbreviations, BUAH, and save him valuable moments multiplied by the hundreds or thousands of times he says it every day. All that time could be used for learning more Torah!

According to Actualic, someone went to Rav Chaim to consult on an issue and before leaving he requested a bracha. When Rav Kanievsky blessed him with BUAH, the talmid chochom visitor asked that by the halachos of counting the Omer we see that if one counts using the abbreviation of the number rather than the full number he needs to recount that day - meaning, if he counts saying today is yom bet laomer, or yom yud gimmel laomer, etc, rather than saying today is the 13th day of the Omer. So, using an abbreviation is clearly not like saying the words, or else by Omer it would be acceptable. So, the rav asked of Rav Chaim Kanievsky, why do you bless people with the abbreviations rather than the full blessing, if the abbreviation isn't considered the full statement?

According to the article, Rav Chaim appreciated the witty question, and responded that counting the Omer is an actual mitzva, possibly even Torah-mandated according to some opinions, but what I do isn't really anything and can therefore be shortened.

Combining that with other statements made by Rav Kanievsky recently about his abbreviated bracha, because he means the same thing for both the abbreviated version and the full version, there is no difference and for a bracha it is perfectly fine, and he proved from a gemara that giving a blessing with abbreviations works.