Aside from an impromptu font trip a few weeks ago, I pretty much stopped climbing after my finger injury.
I had the odd wall session, the odd outdoor session and a comp between then and now. So maybe an average of 2/3 times a month, but all sessions felt fairly intense.
I have actually found that I can pull as hard now (rock and plastic), as when I was climb 3/4/5 times a week. Although I am not as fit as I would have been.
I think if you make the sessions you do have count, and do the odd supplementary set of generics i.e. situps, pushups and the like; you can remain fairly strong, even with the order of many weeks off. And those who have been climbing for long enough to have adapted well to the exercise, will be able to remain at a base level with relatively fewer hours on the wall.
I also put great stock in the idea that the body goes through cycles of physical and mental power, and that its important to account for this (and not get too frustrated). I have no academic evidence of it, but I have felt and seen in others that even keeping a steady pace of climbing and work/life stuff, you go though phases of more or less power.
That said, I am just at that point where my body is starting fully to adapt more for the exercise, and as such I expect fewer, hard sessions contribute to the effects of adaptation, recovery and the likelihood of injury.
It also could have been that with correct periodisation and more time on rock (to learn to climb better), I could be climbing much harder stuff that the 7B kind of range.
The caveat is that, I don't expect you will see much in the way of improvement; If you are used to improving or even just seeing fluctuations in quality, then your self-perception of how well you should be doing and are doing may be skewed by this. In turn you will think you are doing worse and/or better than you are/ are capable of. It is all relative, right?