The Issue Of Shortening Salah (salat-ul Qasr) During NYSC Camp - Islam for Muslims

Asalam alaykum.

This issue of Qasr stirred some controversy and debate while I was in camp recently. I think the major problem was with regards to the actual number of days it is permissible for a traveller to shorten his salah as scholars have differed over this . Some say 4 days, some 15 is maximum, some say since the prophet (peace be upon him) was never reported to have shortened his salah for more than 20 days, then that is the limit. And I've also read views which say that some sahaba while on jihad performed Qasr during that entire period which amounted to about 6 months and thus Qasr is valid for a traveller for any length of days so long as he intends on leaving there once the period is over.

During a lecture organised by MCAN in camp, the speaker's view was that it was better we observe the salah in full. Put in mind that the average camp period is roughly 21 days (even though this last stream spent 18 days).

I would like to hear the opinion of knowledgeable brothers and sisters here regarding this issue (with evidences of course) and also those that must have encountered this same issue during their service year.