Hi Mathew;
It really depends specifically on the unit.
In Ontario - and I realize you are based on Alberta - condo corporations hold capital insurance. Capital insurance has two components - liability and fire insurance coverage that restores the unit to its ORIGINAL state with ORIGINAL(or today's equivalent standard) finishing materials.
If your unit has an upgraded kitchen or bathroom, it is likely that $15,000 would not be enough (the condo corporation's coverage, in event of loss, as an example, would provide a base kitchen/bathroom, not an upgraded one). On the same token, I have some clients that feel they are adequately covered by the condo corporations and policy and do not take out ANY supplemental coverage.
On another note, if you are looking for supplemental coverage there is something called co-insurance (in Ontario - I am sure the concept holds true in Alberta). What this means is that if you sustain a loss, and the insurance company feels you were underinsured, they pay amout based on the percentage of the claim. As an example, if you should have been covered for $30,000 (as opposed to $15,000) they will pay 50% of the loss. A good shock for the policy owner...
Without a doubt, its best to consult with an insurance broker.
Mike