I appreciate the responses. I forgot to mention I use poly. I think I just need to learn to differentiate the feeling between new and dead strings. I only recently became more proactive in tennis, so I suppose I'll need more play experience before I get to that point. I'll probably rotate my racquets to wear them out evenly, like suggested, and try to pay attention and get familiar with my strings.
An idea I was considering: play with the same racquet for maybe like three months, then switch to the other. If poly dies as quick as I've read, then there should be a noticeable difference between the two. I'm not sure how fresh the strings on the other racquet will be after three months and my game will probably suffer, but this tactic might be more effective in helping me to identify the difference.
As for the backup idea, my current two racquets were purchased at a bargain but used. As it turned out, one of the racquets had obvious scuff marks on the bumper and on a couple parts of the frame while the other was nearly pristine. It might be silly to attempt to preserve its condition when normal wear and tear is inevitable, but that's just me being weird.