A saakin letter may have 3 different durations depending whether it is RIKHWA, SHIDDA or BAYYINA/TAWASSUT

Question
Assalamualaikum

A saakin letter may have 3 different durations depending whether it is RIKHWA, SHIDDA or BAYYINA/TAWASSUT according to the teaching of Shaikh Ayman eg 'ASS'is longer than 'ALL' which is longer than 'AK". Does the same rule apply to the first letter of the mushaaddad letter eg in the word "AS SHAJARATA", should the first sheen be prolonged just like how it would have been done if it was a saakin?

Jazakumullah

Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh,
Yes, this is correct about the timings of the saakinah letters and yes, the same timing applies to the saakin part of the shaddah, since the first letter of the shaddah is saakin.  The timing will be the same for the saakin letter and the same letter with a shaddah, there would be no difference in the timing for the same letter. 
Wa iyyaakum.
Wa assalaam alaikum