When there is a letter with a sukoon after a stretch, as in the first 3 examples, stretch for 2, 4 or 6 counts. This also applies if there os a letter of 'leen' after a sukoon. Leen is when a wow or ya saakinah is preceded by a letter with a fathah (last 2 examples).
6. Six-Count Stretch - with Shaddah and without - within a Word
We must stretch for 6 counts when there is a letter with a shaddhah after a stretch, as in the first 4 examples, or if there is saakin letter after a stretch (last example).
7. Rules of Reading the Disjointed Letters (Surah Openers)
Some Surahs begin with certain disjointed letters, such as Alif Laam Meem. These letters are: alif, ha, Ha, Ta, ya, kaaf, laam, meem, noon, seen, 'ain, saad, qaaf and ra.
The alif has no stretch. The ra, ha, Ha, Ta and ya are all stretched for 2 counts. 'Ain is stretched for either 4 or 6 counts. The remaining letters are all stretched for 6 counts.