The usage of 'if at all'

[Leong187]

Hello.

Can anyone explain to me the usage of 'if at all' and provide me with some examples?

Thanks in advance.

[Mordant]

"If at all" means something we just dismissed or presented as weaker than thought may even be altogether untrue.

Alex was only slightly angry if at all. He still looks forward to meeting with you.
After years of abuse, the singer's voice was marginally effective if at all.

Alex may not be angry at all.
The singer's voice may not be effective at all.

It's often a way of stopping just short of total disagreement.

[Leong187]

So what's the meaning of this sentence 'We'll only do it once—if at all.'?

[Mordant]

We'll do it only once or possibly never.