Excuse is an explanation to justify something that you didn't do right and it is not tolerated by so many people. Who doesn't hate excuses tho? No one, I presume.
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Imagine on a Monday morning, as a boss you sent an email to your staff to carry out a particular assignment which you set a deadline for Friday and to the greatest of your disappointment he or she didn't get it done. You summoned the staff and he started giving flimsy excuses of not having internet, not having enough resources to carry it out or even the most annoying excuse that he forgot.
Let's also consider that your friend that you work in the same company, receiving the same salary as yours got a new luxurious apartment and you were invited for the housewarming. You went with your children to the ceremony and they all saw how beautiful the house and its environment looked with nice interiors, exteriors, furniture etc. On getting home, your youngest child was like "daddy, why is your friend's house very beautiful and we're living in a rented apartment?" This might be shocking to you or even sounds disrespectful to hear that from your child. Will you have a good explanation or excuse for your child?
Excuses are very easy to think of. It is the quickest way of exiting a tense situation. Sometimes you get lucky and sometimes you are unlucky. Your so-called excuse may favor you at some point and it could also backfire.
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In the first scenario that I created the boss would be so angry for all those flimsy excuses by his staff and the little child that questions his dad inability to have built his own home when she's aware his friend who did house warming earns the same with his dad would not buy any excuse provided by her dad. It simply means the dad isn't placing his priorities right.
It is better not to wait to give excuses, do the right thing at the right time to avoid telling plenty stories. Make use of opportunities when they come your way rather than not taking the chance and later giving flimsy excuses.