Variant on Preparing Actions

[Othesemo]

The usual rules for preparing actions have always bothered me. Thus, I've created an alternate system. Basically, it works like this, To prepare any action takes as long as would doing it. For example, preparing a Summon Monster 3 Spell is a full-round action, whereas preparing to step ten feet to the right would be a move action. When preparing the action, you describe which circumstances will cause you to use the action. Until the action is used, or you cease to prepare, you will continue to have to take said action every round. Full-round, move, what have you. For example, if you prepared a five-foot step, you would be unable to take any swift actions until you took it.

There are a few stipulations- you cannot have more than one action prepared at a time, and you cannot have an action prepared for a duration of more than one minute.

Any thoughts? More importantly, are there any balance issues present