Whether the fourth rifle company in a battalion would make any difference in our remaining time in Afgh might not really be the issue. The question might really be: why don't we maintain four rifle companies, permanently, as the standard for operations? (And thus, hopefully, the structure in garrison)
In 1994, following our tour in Croatia, our unit (1 PPCLI) identified in our "Lessons Learned" report at that we were badly hampered by trying to run a large, busy AO with only three rifle companies. The result was a very thinly dispersed force with limited rapid response capability and long transit times over very predictable routes. Thankfully, although we faced challenges and lost people, we didn't confront anything like what Canadians have faced in Kandahar. It seems things haven`t progressed all that much.
In understand the institutional pressures and compromises that led us to basically shelve the fourth company, but IMHO it is a must for operations.
Cheers