Definitely. While it's not a perfect solution, it provides an extra layer of protection for your accounts by making an extra hurdle for any attacker to clear. Needing two components to access/change your accounts is elegant and effective.
Pay-as-you-go phones are advisable to use for two factor verification, as they are affordable and could be used only for this purpose. Don't hand out the number and you've got a nice disposable tool for protecting your accounts.
Many providers shuts down the account if you don't use it for calling at least once per year. Some close it down if you don't fill up the cachpool with money every 6-12 months.
Right, pay-as-you-go phones are annoying that way, if you aren't actually using them. I've lost a few phone numbers because I didn't remember to top-up a phone I wanted for rare uses and/or only incoming calls.
Pay-as-you-go phones are advisable to use for two factor verification, as they are affordable and could be used only for this purpose. Don't hand out the number and you've got a nice disposable tool for protecting your accounts.