Progressive overload over time is key. You can do this by doing more weight or adding reps. I think if you are on a split and train a group once per week, you should be able to add weight to the bar each session, but perhaps only on your primary movement. People who do, say, 3-4 movements for chest and 3+ sets per movement are going to have a hard time doing that.
The whole "one work set taken to failure (and beyond, perhaps)" thing has been harped on a lot here lately and there is a strong little contingent that preaches it, but I think that's only one way to do things and may leave a muscle underworked, at least where earlier sets are essentially only pogressively heavier warm-ups. Strength is important, but in terms of hypertrophy so is the work performed. So, a top set of military press of 225x9 may not be as effective for hypertrophy than 2-3 work sets of 210 for 8-10 reps each.
I have found that 2-3 "work sets" (not taken to failure but getting close) for 1-2 movements per group done 2x per week is a nice balance and creates on overall anabolic environment for your body to grow- for a natural trainee w/ normal genetics, this is a better approach than the "trash the muscle with tons of sets" and the "one work set taken to failure" extremes.
So, to answer your question, if your working with 210 on incline bench and getting 8-10 reps for 3 sets, up the weight for your next session and see what happens. If you are still getting the reps for your first 2 sets next time with the higher weight, up it again for the 3rd set to challenge yourself.
Others have said that increases happen linearly- I haven't found that weight increases linearly very often. More often than not, I will increase by 10 lbs, stay at that new weight for a bit, then increase another 5-10 lbs. Granted, there are 2.5-5 lb weekly increases from time to time but having an expectation of "adding weight to the bar every session" make for good forum posts but may not play out in reality. This is similar to the disastrous rhetorical question regarding mass building- "is the scale moving?". People then get it in their head that weight gain should happen constantly and perceptibly, when in reality 8-10 lbs of lean mass gain in a year is fantastic progress.
Adding weight to the bar and mass to the frame is glacial. It takes years and years. Otherwise we'd all weigh 300 lbs and deadlifting 900 lbs.