Is it possible to be reasonable all the time? The answer is yes, when understood in the right context. The right context is one where the thinker has determined that reason is his only tool for cognition. If that is the case it would be the height of folly to choose to ignore or violate your cognitive faculty. You essentially automatize your subconscious to never betray reason. You make it a habit. The longer the consistency, the stronger the faculty. In my case I made a sort of pact with a man some five years ago that promised our mutual devotion to reason. This was my first time to make reason explicit. Several times in my life there were implicit devotions to reason that generated an inductive argument pointing to the power of reason, but it wasn't until I made the promise explicit that I was able to understand the full power of the previous implications.
When understood and adopted as a way of life, reason lives up to Rand's highest expectation, it works.
Practical application: Reason refuses to voluntarily promote the irrational. It is irrational to replace an argument with a gun. It is irrational to support a government that violates the rights of its citizens. It is irrational to support a government that uses force as a tool against the innocent (ie, no right has been violated inviting force in retaliation). Consistency requires the reasoner to avoid contact with those who violate reason, as much as possible. I am saddened by the number of people who argue it is reasonable for the government to force us to pay taxes. If you have to force them. you can't claim you are being reasonable.
The more explicit I make my arguments against the variations on subjectivist thinking, the greater my isolation in today's world. My life is literally dependent on winning this argument. Yours is too, if you didn't get that far.