I heard some reciters of the quran elongating madd tabiee more than 2 counts.

Question
Assalam o alaikum
I heard some reciters of the quran elongating madd tabiee more than 2 counts .Is it a different way of reading the quran or is it an incorrect way?

Answer
Wa Alaikum Aassalam Wa Rahmatullahi Wa Barakatuh,
The natural medd or is always lengthened 2 counts, not more or not less, for all the ways of reading. There is no difference in reading for  the medd in any of the different ways of reading the Qur'aan. To read this medd longer or less than two counts is a mistake.
The length of a vowel count is based on the speed of one's reading, ie based on the length of each fathah, dhammah, or kasrah, which should all be equal, and for the time of a single vowel is mulitplied by two.  Readers have different speeds of reading, so it maybe that one reader is reading at a quicker pace than another, or one is reading slowly;  the lengths of each of their vowel counts cannot be compared to each other, instead each vowel count is based on the speed of their reading. 
It is not correct to time the medd by anything other than the timing of two vowel counts based on the speed of the reading. 

Barak Allau Feek,
Wassalam Alaikum