Question

Assalaamu alaikum wa rahmatu Allah.

The correct timing of the leen letters, (that is the ya saakinah or wow saakinah following a letter with a fatHa), such as when reading the word  or (when continuing), needs practice it seems to me; because these letters should not be said so long as to be like a mad tabee'ee i.e. two counts nor too short so that they don't have their characteristic "rikhawah" i.e. the longest prolongation of the sound in pronouncing a saakin letter.  Would it be possible to give us an example we could follow of the correct timing of these letters and any further explanation that could help? 
Jazakum Allahu bi kulli khair!

Answer

Wa alaikum assalaam wa rahmatu Allahi wa barakatuh. 

It is not an uncommon mistake for non-Arabs to either cut short the timing of the leen letters or prolong them.  The timing is usually quite natural to the Arabs, and it is infrequent that they have problems in the timing of these letters. There are a few techniques to help the student in this endeavor.  The first thing is being careful that the timing on the fat-h before the ya' or wow saakinah is the same timing as all the other fat-hat when reading.  Those that prolong the timing of the leen tend to prolong the timing on the fat-h more than one vowel count.  The second thing to do is to make sure to go directly to the wow or ya' after the fat-h and put pressure on the articulation point of the letter, either the  by circling the two lips, or the , by lowering the jaw.  Another point is to make sure the fat-h is not pronounced with "imaalah" meaning half way in between the fat-h and kasrah.   If these articulation points and the proper fat-h are not used as they should be during the pronunciation of the leen letters, the  of leen sounds more like an English "oh", and the  of leen sounds like the English long "A".  As pointed out in the question, both the  and the  have the characteristic of , meaning the sound runs with the letter.  The running of sound though, is on the  saakinah and  saakinah of the leen, not a prolonged fat-h before it.  If the sound is not run as required in the intrinsic characteristic of , the leen letter will be too short.

These are just a few tips to help out, but in the end the ear of the Qur'an student needs to be developed so they can hear the difference between the correct sounding leen letter and its timing and the incorrect one.  The development of the ear for the timing needs to be done by listening to masters of tajweed recite, and being corrected by a qualified teacher.

Wa iyyakum wa-muslimeen.