A couple of weeks ago I wrote on the idea of position before submission. That is a common philosophy of grappling but it sort of falls short of the potential of the holding technique in judo. A position can and should be a submission in and of itself. The purpose of a judo hold is not only to immobilize uke, but to make him so intensely uncomfortable that he may just submit from the hold.
For example, the judo holding technique katagatame (the shoulder hold) is known in jiu-jitsu as the shoulder choke (See Renzo Gracie's Mastering Jujitsu, p193 for an interesting variant) because the pressure of tori mashing uke's shoulder into his neck is so intense, unless uke is pretty sharp and pretty fast, he'll likely submit from katagatame long before he gets to escape it.
Another great example that is ultra-common is the positional asphyxia trick used in most side-position hold-downs. The idea is to compress uke's floating ribs into his diaphragm and hold tighter every time he exhales. Pretty soon, with tori's weight resting on uke's diaphragm and his chest wall in maximum exhalation, there is no way to inhale. This is a vey frightening submission.
Per conventional wisdom, I recommend that you pursue position before submission, developing good holding skills and good transitions between holds. But if you have previously only thought of holds as platforms from which to launch a choke or armbar, then re-examine them from the point of view of making the position itself into a submission. This will improve your judo game tremendously.