I am told that on All Souls day if we make six visits to six churches and say designated prayers, the souls in purgatory for who we pray go straight to heaven. What do you think of this?

There are many danger signs in the practices you describe. We ought to be cautious about various spiritual practices or exercises that have many different moving parts, or complex requirements. We ought to be even more suspicious of unqualified and overly certain promises of success. 
 
At the heart of indulgence practices is a very proper notion that prayer has salutary effects. However, prayer should not be reduced to superstitious practices. We cannot force God’s hand; neither should prayer be likened to magic which seeks to manipulate reality. 
 
Every pious practice and prayer is always submitted to God's will; and through these things we commend ourselves to God's good graces, knowing that he will answer in ways that are ultimately best for all involved.