God is not confined to the parameters of time, as we are.
A prayer or sacrifice for someone now will be known to an eternal God when that person for whom the prayer is offered comes before Him for judgement.
It is a holy and wholesome thought to pray for the dead. Your prayer for a suicide could be the intercession that caused a last second conversion, or that influenced the eternal God to grant salvation. After all, no greater love does one have than the love one shows in giving his life, his love, his prayers, for his fellow man.
"Blessed are the merciful, for they shall receive mercy"....
I would agree that it is "holy and wholesome" to pray to God for someone -- however while they are still alive that they may find strength through that prayer in the belief of redemption through Christ. Salvation must be earned before a mortal death.
In other words, if Christ's gift of redemption had not been accepted during this lifetime, no amount of "intercession" and "influence" on behalf of an unbelieving soul will apply in our next "life."