As I see it, only you and your bandmates can answer this, because it depends on what you want to do.
First off, if you're not gigging... what exactly are you rehearsing for? Someone needs to step up and book gigs, or else I don't see why there's a band in the first place.
Assuming you have gigs at some schedule, then I see rehearsal potentially doing three things:
- Song inspiration
- Song writing and refining
- Gig preparation
Jamming is good for the first two. Completely free-form jamming helps with 1., while repetition of a new song with inspired changes helps a lot with 2. To me, the best gig preparation (3.) is actually repetition. In my bands, we have made our setlists in advance and then rehearsed (and in some cases timed carefully) our setlist in order with no breaks straight through, even twice for some rehearsals. I suppose some may find it boring (I love playing anything, any time so it's never boring to me), but it does make the gig run really smoothly and even helps one deal with the unexpected.
My favorite band schedule for the song phases above is actually more like what your bandmates like, with one change: I want a separate songwriting night, and that night is only for song writing. I also like song writing to be more intimate, not a band practice environment but just acoustic instruments in a living room or something. I like having portable recorders and pen and paper nearby and the lyricist would have their journals and lyric books available, etc.
Then a full band practice starts with a jam to loosen up and warm up. Then, yes, running down our weakest songs to make them stronger, and then jamming out/running down on the new song ideas from the last writing session. The last phase of that kind of rehearsal usually involves lots of stopping, working out transitions, trying different sounds, etc.
When a gig is imminent, my bands have often doubled up rehearsals, halted all new song work, and just focused on running down the set list once or twice at each practice, possibly repeating sections or songs that are not clicking quite right.
To look at it from the other side, striving for perfection isn't bad, IMHO. If your band is somehow playing even one the your songs perfectly, well... frankly I'd wonder what things aren't quite right that you're not even aware of. Because it's never possible to literally play something 100% perfectly. There's always room to rehearse it one more time.
That said, if you're not gigging then you're not getting paid, which means you're hopefully doing it for fun. Keeping band practice fun is very important, IMHO, since you want gigs to be fun so the audience has fun and you don't feel bad that you're only taking home $20 at the end of the night.
Jamming, writing, and repeating all have value, and you'll have to find that balance for your band. Not only should your bandmates recognize the value of jamming and writing, you should also be open to the value of repetition. I highly doubt that repeating songs you've "already learned" isn't helping you play them better. I've never achieved or seen 100% perfection on a song, so if you're somehow 100% perfect in your band then you should really book gigs because I want to go see that.
On further reflection, I feel like your bandmates are more objectively right than you are. You mention that you "already know" the songs you are rehearsing, but knowing a song isn't the point of rehearsal any more than merely playing songs you know is the point of a gig.
Unless we wrote a number less than two weeks ago, I expect myself and my band mates to know every song we are going to rehearse before practice. We're playing the songs we already know in order to explore deeper nuances in the songs, foster our communication with each other through the songs, and enhance our communication with the listeners through the song.
You should know your part backwards and forwards before practice. During practice, you should be listening to everyone else and the band as a whole with an ear towards moving as one and getting the right feeling.
You want to listen as a band member and really learn how your fellow bandmates are playing and feeling. If you can tell who had a bad day or a long week of work or who is in a really good mood or who is distracted while you are playing a song from the way they play, then you're in the right track. If the drummer or the bass player can change one note in the second chorus as a little joke and it actually makes you laugh while you're playing because you both hear it and get the joke, then you're doing something right. You should be listening to every sound that everyone is making and not only working to make sure your part is fitting in and enhancing the song, but also making mental notes on what others are playing to either compliment them or suggest changes. Band practice is much more about listening than playing.
You also want to listen like an audience member. Do you just like your own songs? They should be some combination of fun to play and/or fun to listen to. If not, what could you change about them to make them better? Would you want to buy your own CD and go to your own gigs? Could you insert a musical joke that your die-hard fans would get? How is the balance of the instruments? Are you too quiet? Too loud? Should you actually drop out in the second verse because the singer is hard to hear then? All these things. Again, it's about listening, not knowing or playing.
And ideally you would not merely know the songs, you would transcend them. You want the whole playing or the song as a band to be so automatic, organic, natural, and easy that you're not even thinking about the playing, instead you're participating in a collective emotional experience for which mere words would not suffice. And you want to be able to include audience members who aren't even musicians in that experience. Merely knowing the music is only the first little step in making that happen. It takes a lot of hard work, and yes, repetition.