This is my first post on this forum, although I've found many threads and other technicians' comments that have been very helpful to me. If this has already been discussed please let me know, I did try to search for it.
I've had the opportunity to come back to many pianos that I've serviced before and after NBSS and I'm trying to decide which pianos to fine-tune or pitch-correct, and whether to charge my returning clients for a pitch-correction tuning on every appointment. I find here in Boston and north, if I tune at the beginning of fall in September, many pianos are still as sharp as 445 (that's measuring A4), while in the middle of winter, pianos are as flat as 435. Is it acceptable to tune mid-fall and mid-spring and not worry about the tension on the pinblock or soundboard (and tuning) at the peak of each season? Is it acceptable to tune to A442 in the summer and A438 in the winter in non-concert settings?
I know some techs who will do a pitch-raise on anything outside of 439-441 and I know some who will use the "pitch-raise" mode and do a once-over fine tuning on anything that is within 25 cents. I do use an RCT and I do recommend and install the Piano Life Savers when appropriate. My question is what are your parameters for pitch-raise vs. fine tuning and when do you tune for your twice-a-year clients?

I have found over time that any piano more than 3.5 cents (approximately) away from pitch will require a second pass.
Also, I have made it a habit to make two passes on most tunings. First pass only adds about 20 minutes and creates much more stability. I have included it in my standard tuning fee so I do not need to explain extra costs and pitch corrections - some people feel scamed by such stuff. Makes my life easier.
Whenever I tune, I tune to 440 unless the customer requests otherwise. I do not try to anticipate climate change - it is beyond my control.
If the piano is drifting unreasonably I suggest humidity control.

Like Gene, I always do two passes and I always raise pitch to A-440 no matter how flat the piano is. I usually only charge extra for a pitch raise when the piano is flat enough to require extra effort and time beyond what I can do in my regular service call. The customer understands that it is going to cost more if the piano has not been tuned in x number of years. I don't feel right about charging a pitch raise fee if the piano was just tuned within the same year by me. For me, raising pitch has almost become an effortless procedure because I've done so many pitch raises. I almost get bewildered when the piano does not require one.

However, sharp pianos are a different story. Around here pianos can go sharp quickly during the latter part of summer and then fall quickly in October when the Santa Anna winds blow in. I don't mind tuning a piano sharp and I've never had any complaints. However, if the piano is going to be used for a recital, concert, or recording I will lower the pitch to A-440.

So I guess you can say that in my belief, sharp is ok but flat never is.

IMO tuning stablity has preference over pitch in most non-instituional situation. IF the piano is regularly used with other instruments, digitals, organs, etc you are more or less compelled to keep it a pitch. That means more frequent tuning as the board shrinks and swells. In the home however if a piano is 435 during dry season or 444 in humid conditions and relatively in tune with itself pushing to pitch and the attending instablity does not serve the customer.

In my experience up north, C4 may slip to A-435, but C6 may be A-437 and C7 and C8 could be at 440. C3 may be at A-438, and C2 at A-440. So if pitch isn't an issue, evening out the pitch by measuring several notes may be best. If you tune the whole piano to A 435, you are moving the bass pins at every change of season, which results in premature loose bass pins - (bass pins are usually a bit looser to begin with). I might pull the middle up 10 cents, lower the low treble a bit and accept more of an octave stretch than normal, leaving the top octaves where they are. Same concept in reverse in the bass. Less movement of pitch = more stability.