Sort of. I like the idea of paying off all debt (an uncomfortably large mortgage), but also realize that may not be the best move financially. Even if it were the best financial decision, it does me no good in terms of risk reduction to pre-pay unless I have enough to pay it all off. My outlook is that I have a job that is at high risk of being cancelled, and my monthly mortgage payments are high. If I pre-pay and don't save that money for when I don't have income, then I'm at risk of losing my house AND my savings. So I stash my cash in an investment account and watch it grow. When it gets large enough to pay off the balance of my mortgage, I may, repeat may, use it to pay off the mortgage. By the time that happens though, 2 things are likely to be in effect 1. I'll have seen the effect of compound interest and will be able to compare the benefits of both methods so that I'll decide to keep it in investments and not pay off the remaining balance; or 2. I'll be so rich by then I won't feel the same pressure to pay off the debt.
So I think of my taxable investment account as my sinking fund for paying off my mortgage.