I usually carry about 7 balls in my bag. About 3 of them are new usually.

Usually 6-7 are in my bag.  An open sleeve and a full sleeve and a couple of used Pro V1x's.

I usually have two sleeves of new V1's from last year. I need to lose those before I switch to the new model. If I'm playing a practice round I'll bring 9 out of the shag bag (V1's and 1X's from various years)

I only carry 4-5 in my home course but if I am playing in a course that I don't know I carry about 7

I always keep 12 balls in my bag so I can rotate if needed throughout the round etc... sounds like this is common for most...great thread!

I usually like to carry a dozen in my bag per round. I don't keep any found balls as a like to play the same ball

I keep 2-4 sleeves of ProV1x's in my bag, new.  And usually a handful of good used ones from previous rounds.  I also have a handful of found balls in the bag, until I decide to go thru it to give them to the kids, usually for there golf practices.

I carry too many balls in my bag probably. I have two pouches. One is dedicated to "gamer" balls (mostly ProV1x) and other "tour level" balls I find on the course I probably keep 9-10 or so of those. The other is dedicated to balls that I've scuffed up or cheaper balls that I've found. I'll keep a few just to mess around with if I'm playing by myself but take the rest home to chip around with in the backyard. 

I usually keep a dozen balls in my bag for each round.  If I find any balls on the course I add them to my shag bag along with any scuffed balls during my round.  I will keep a couple loose balls in my bag if they are left over from a previous round and are still good.

I carry between 6 to 12. Only one or two are left overs from the previous round, the rest or new. The extra balls help to balance out the carry bag when I walk the course.

I only pick up found balls if they are obviously abandoned, barely used, and if they are a Pro V. Otherwise, I leave them at the next tee box so that they don't confuse other players on course and slow down play behind me.

Usually between 6-9 balls w/ 3 of them being new. I also tee up the last ball I used for my next round. I collect all the extra balls I find for my friend since he is a beginner and he loses a lot of them. 

I usually have a dozen new balls in my bag and about 3 or 4 used balls.Any non Titleist balls that I find I give away and any Titleist balls I find I put them in my bag and when I clean out the spare ball compartment they go to the shag bag,

I generally carry about a dozen.  Wish it could be less, but I've been struggling mightily off the tee so far this season and been losing a ton.  

about 2 to 3 new sleeves of ProV1s and then about a dozen used balls...  I have a push cart so the weight is not an issue and I never know what my game will be like that day so i like to be prepared... 

Depends on how I've been playing, but I usually carry somewhere between 6-12 balls. I used to keep more in my bag, but that was before I started carrying (my push cart broke last season and I haven't replaced it yet). I'll typically keep 2-4 used balls for holes where I think I might lose one, but I've started building a stockpile of ProV1s so that I might not have to bother with such things one day.

Always 6-8!

i need more than that and I'll be on the range putting work in.

I keep a dozen in my bag. 9 prov1x's, the rest NXT Tour. 

Usually start with 9 or so, 6 used, and (1) new sleeve. Unless it's a round that means something, than, (3) new sleeves.

I walk so I try to go as minimalist as possible.  But I still have anxiety about running out of balls on the course even though it's never happened to me. That being said, I carry one new sleeve of Pro Vs, two sleeves of used Pro Vs, and one sleeve of NXT Tours.  I still pick up apparently lost balls for my shag bag but it's amazing how many Pro Vs one finds.

6 Pro V1x #21 JEC2

Two new sleeves, one opened sleeve and 1 to 3 prior round used balls. If I find a good ProV 1 or x on the course I will put in the bag to transfer to the shag bag.

So 9 to 12 balls

I carry 3-4 new Pro V1X balls and 5-6 used balls(other brands)

I Generally carry 9-11 balls in my bag. They are all Titleist pro v's, some are well worn, and some are new, or close to it. The thing is  they are all found balls. I will find balls, and keep the ones I want to, or give the ones I don't want to the bag guys at the clubhouse to use for themselves. I try to use only the newer generation titleist balls, but when I come across one of the hyped balls, I'll keep it to try out when I'm playing by myself. I can honestly say, I can't remember when I bought any new balls.

Normally two to three Prov1s in my active pocket with a few tees, Titleist ball marker and favorite divot tool (don't get on the course without one of these).  One of the balls in that pocket might be one I am playing waiting to be retired.  Keep one to two new sleeves in my storage pocket.  If I find balls on the course I give them to my buddies, unless they are new Prov1s.   ONLY ball I play.  

Depends at which hole you pose that question, this beginner can be down 2 sleeves just by the turn.

6 golf balls

1 the last ball used from the prior rund

5 new

I put 3 new balls in with 6 used balls.  Change ball every 6 holes.  If I find balls on the course, depending on the condition,   I keep them,  put them in my shag bag or use them on the range,