In my experience, the quality of the tube makes a big difference. Some low quality tubes are somewhat porous, so that over time, they lose pressure. In addition, their wall casing tends to be inconsistent, causing a tendency to bulge badly - obvious if you blow them up a bit before inserting them in the tire. This can cause the tire to either bulge a bit, or even be a bit out of round.
I have had good luck with "Michelin" tubes.
Check out converting your tire to 'tubeless'. Its a lot better than solid tires at the least. I have tried just about everything on my 29" bike. I had the same issue with a leak not less than a week ago. First I tried making my own patches after a few days of exactly the same thing, filling tire every morning, re-patching, trying to glue and tape, I decided to just get rubber cement, and patch kits, sand paper and do it right. I did not have a leak in the actual valve stem as of yet though, not sure what I would do there. Just small punctures either single or "snakebite" doubles from rim pinching on impact. Patch kits and rubber cement are great, but wouldnt it be nice to be flat-proof and retain the ride of air filled tires? Im hoping I found a solution...
Today I am actually going to convert my tires to tubeless while im painting everything etc. I have been researching this and really like this option. I do a lot of up and down, sidewalk edges, rougher pavement, bumpy sidewalks and even some grass/field riding when I cut across parks etc. If I was pure road mileage on smooth blacktop I would actually get as close to slicks as possible then for sure use inner tubes and go really high PSI like 50+. But my rides are rough and full of surprises, especially since my headlight visibility is very low.
I am reading that a lot of mountain bikers are going tubeless, they let some air out for traction on really rough terrain(doesnt apply to me) and they all use a sealant liquid that makes the tire pretty much flat proof. Ive seen a few ways to do the conversion. "ghetto": Use an inter-tube and cut it down the middle after wrapping it on the rim, just leave the valve stem in the old inter tube lol,( works actually well if u get an inter tube size smaller than the actual rim, like stretch a 20 inch tube on to 29 inch rim). then soap it up, slap tire over it, pour in slime/sealant add air and pray. If you dont have the right kind of tires and rim that are designed to lock together etc. its a huge pain.... first time I tried this, basically my entire room was covered with the sealant , ahhahah no matter what I did it would not seal, and just leaked and sprayed everywhere. OK, this nab is going to shut off the ramble here and get started on paint, tube less conversion, cant wait to see how it rides after.