I would not see this as a problem, necessarily. If heaven is understood as a place outside of time, then there would be plenty of opportunity for Mary to handle her intercessory duties.Steve made a good point concerning the inability of any saint in heaven to be able to hear and respond to the countless prayers that may come Mary's way.
I'm not sure if this would qualify as "prayer" or not; the answer would depend upon one's definition of prayer. The communication would not necessarily connote worship or idolatry.The arguement went that the catholics do not pray to Mary but ask Mary to intercede, in effect, to the Father and they are not really praying to Mary. My comment/question would be that in asking Mary to pray to the Father on their behalf, wouldn't this be the very same as praying to Mary...?
I am not fresh in my acquaintance with Catholic doctrine on the saints, but an appeal to Mary for intercession might be considered more or less parallel to asking one's bible study partner for prayer support - though Catholics probably often feel that Mary's efficacy is greater. This whole view may tie into the Catholic concept of the communion of saints, participated in by both those who are alive on earth and those who are with God in heaven.
This touches upon what my concern would be, viz., the seeming prohibition against spiritism. I'm not sure how Catholics deal with this issue. Mary may not be considered to have ever died, in light of the dogma of the Assumption of Mary into heaven; however, calling upon other saints would not have the undergirding of the assumption dogma....and in the very least conjouring up a spirit in order to communicate with God?
For my own part, I think the dead are flat dead in the grave, so they're not presently interceding for anybody.
Shalom,
Emmet