Is it necessary to read al-madd al-`aarid li-ssukoon with the same number of counts throughout the recitation?

Question
Assalamu `alaykum

Is it necessary to read al-madd al-`aarid li-ssukoon with the same number of counts throughout the recitation?  For example, if I read it with 2 counts in one ayah, is it necessary to read it with 2 counts whenever it occurs in the recited portion of the Qur'an?

Jazakumullahu khayran

Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh,
It is considered proper recitation to be consistent in the lengthening of throughout a particular sitting of recitation.  If one makes a mistake however and lengthens one longer than the other, it is not haram, just not the best presentation.  It is certainly something we should all strive for in our recitation. 
If you are a teacher however, it is quite important that you are consistent in your throughout the recitation, and it would be expected you correct yourself in this setting, if you made a mistake, to drive home to the students the best recitation methods. 

Wa iyyaakum.   Wa assalaam alaikum