In the amount of time you are talking about a ball will not break down internally.  The thing to keep an eye on would be how well the cover is holding up.  If the cover is good on a ball i'll keep playing it for as long as I can. 

You've got to be careful though cause even a very small disturbance on the cover can alter the ball flight.  Unfortunately even one bounce on a cart path can ruin a ball.

Thank you...,

iGentlemen..... I thought the same... Hit 'em good...

MANY TIMES I HAVE PLAYED WITH THE SAME BALL 3-4 ROUNDS. I DON'T HIT IT VERY FAR(13 HDCP) BUT AS LONG AS I DON'T SCRATCH IT UP BADLY I KEEP ON PLAYING IT.

Unless it gets scratched, scuffed, or dinged I'll keep playing it.  I did rocket one right into a rock, and I swear the flight was just wrong after that.  That said, I don't know if balls wear out from being hit by clubs only.

Here's how I judge it. Clean the ball after every hole. If something will NOT come off, such as a cut, a shaving, a scratch, then the ball is unfit for play.

Whenever I start a round with a brand new Pro V1x, after about 2 full rounds it is normally scuffed up beyond belief. By this time I would never use a ball in this sort of a state for a 'competition' round and these balls will only be used as practice balls for the club in practice rounds, so a new ball is needed again for competitive rounds. A scuffed up PRO V is still better than any Callaway or Bridgestone Ball in my opinion!!! 

I use a NXT Tour and even with slight groove marrs to it, kinda how it shows a bit of a scrape on the top of the dimples, ill still play it and not see much difference in preformace, Internaly you will be amazing they basicly last forever from poundings. The cores and mantle is made to be hard enough that even a tour player cant deform the insides. Cant say the older balls are like this. My dad has a maxfli he crushed 290 with his 3 wood and put a flat spot on it. But that ball is back from the erily 90s. So needless to say the ball is fixed in that department. I usually toss my ball to the "shag bag" when the cover starts to get "hairs" or hits a tree/cart path/sprinkler box/rock/ect. Now at a really low handicap and very consistant player the little marks i continue to play with, you can see the difference compaired to me. Tour players switch their balls out on course quite oftin because the slightest nick in the cover can chance their preformace and even with the new grooves they still put alot of spin on it. More spin can really damage the cover.

Bunker play can even damage the covers to so keep an eye on the cover. Dont worry about the ball's insides. Unless you have one sitting in your garage for several years. That can change the compression leaveing a ball or playing the same one for more than i belive it was 2 years. It starts to harden. Now i would belive, dont hold my word to this, sense its a rubber construction that over time and years of crushing the same ball it would start to brake down the rubber bonds in it and losen it up a bit. But if your using a ball for more than a month there has to be something wrong with it, as in being damaged in some way or another. Hope this helps

Balls pulled from the water wear out too.  I pulled, what seemed like, my ProV out of a little creek.  I played it for a couple of holes, and the feel was off.  I checked it out, and it was not mine, although it had similar markings.  I'm pretty sure they get water logged if they sit in the drink for too long.  This ball was pretty new, but it didn't get the same distance and the feel was all wrong.

I will use a Pro V1 for 3-4 holes, then get a new one. Wedges obviously will tear up a ball, but, even hitting the ball on the sweet spot of the club face (irons, woods, wedges...perhaps, even a putter) will do some damage as well. I'll take my old ones and give them to my Pug. He absolutely LOVES to play with Pro V1's! Honestly, he doesn't care much for dog toys, however, he goes nuts over golf balls, and I wouldn't let him use anything but a Titleist!

Anyways...it's all a matter of your own personal preference. As for myself, I depend on my golf ball from the 1st tee box, until the 18th cup. One little slight imperfection could make or break my round. If ANY imperfection appears on my ball after I hole out, even if it's a brand new ball used for that hole, I'll swap it for a brand new one.

I lose my balls LONG before they have a chance to wear out, that way I dont have to worry about it. :)

I will play my ProV 1 for one round, unless  I cut it or mark it up from a cart path. The ball flight is not the same if the ball is cut or marked badly. Compression in the newer balls stays longer then in the older balls. I do miss playing  the Professional!!!

I find that I can play a Pro V1x for about 9 holes before the cover starts to deform. I can tell because the Line I use for putting isn't straight anymore. I have to use this ball though...the feel around the greens aren't exactly the same with another ball...I guess I'm monogamous when it comes to golf balls. I tried the Bridgestone B330-S but it didn't quite feel right around the greens. 

I don't know if mine ever wear out. I just tend to lose one on accasion and that seems to get the job done on changing. That being said, if the ball is scuffed or marked, it goes into the shag bag and I use them to warm up on the range and for chipping only.

I can generally get 2 good rounds in with a single ball. By then the cover is starting to show signs of wear and I usually put it in the shag bag for chipping and putting practice.

I have a moderate swing speed so scratches on my ball usually only happen on a half to full wedge swing. I can generally use a ball until its completely unuseable for maybe 5-6 holes and i use the Pro V1 if you're wondering