usually with this raise in volume, the weights are set somewhat lighter than they were, and people are given a few weeks to work back to their personal records, then try to go past them, invariably they will pass them, and invariably eventually they will stall again...
at this point we usually lower the volume of training, raise the intensity, in some form we will go with lower reps, lower amounts of sets, cut out a day of squatting, something to allow a raising of the numbers... again, the numbers will raise for a while, then stall again.
a this point, another raise in volume is needed, and at this point we will go to the program that most usually associate with the "5 by 5"... squatting 5 sets of 5 with the same weight 3 times a week, lighter on wednesday and heavier on mon and fri. you are all familiar with this i think, we raise the volume for 2-4 weeks, then slowly cut the volume aned intensity of most workouts, going for a big workout every 1-2 weeks, might be a single, a single set of 5, or even one big 5 sets of 5 workout. with people cycling down for a big contest at thsi point we might go for lower reps and try for the big singles.... with someone not at a place where a big peak is needed, its just cycling down to less sets but keeping the reps at 5, and trying to make a pr on a set of 5. this can be repeated several times over and over, but at some point you have to have a period of lower intensity training for a while in between cycles.
i will add that often, for the people with higher goals who want to really train hard, i will start right in with the 15 hard sets a week version, but with weights low enough that they can endure it, and when they get in condition and get used to the volume, will then go back and start at the normal place where rip starts right from the beginning. i find that people who have been athletically active, who have been training on other programs, etc, usually do well with an initial 4-8 weeks of high volume lower intensity training to get them mentally and physically used to this sort of training, get their form changed to a good squat, etc.
this post describes as much as a year of training for most people, with some that adapt well it is stretched to two years.... two years from when they start their initial "pyramid" workouts, or their initial month or so of conditioning with 15 moderate sets a week to when they get through their first real cycle with heavy weights and 15 sets a week cycled down to a peak.
i know this question was aimed at people who have used 5X5 and not me, but id still like to make a couple of comments... there are so many versions of the "5X5" training style, and they are so different. i use this type of training for the people i train all the way from beginners to really good lifters but the program changes over time for each person. generally it starts out in the first week of training with finding your max set of 5 and then very simply working up to one max set two times per week trying to add weight to that one set, with one ther workout in between that is most likely front squats. simple as this might be, it usually works for several months and i am convinced that it is about the fastest way for a total beginner to make progress. at some point this stops working and we go to a slightly different version, probably the one most well known, and also probably the one most usefull to a large number of people. 5 sets of 5 on monday with a set weight, then lighter squats on wednesday or front squats, then on friday working up to a max set of 5. there are some things we do here when it isnt possible to just add weight every week, but for a lot of lifters with minor variation this keeps the squat going up for another year or two. like everything else, it eventually stops working, and we start to add in some more long term variation like loading and unloading. we might do 5 sets of 5, pretty heavy, on all 3 squatting days for 3-4 weeks as a loading period, then back off the volume for 3-4 weeks by squatting for lower reps and only 2 days per week as an uloading period. we might add in speed work or dynamic effort work, using 5 sets of 5 on monday, fronts squats on wednesday, and dynamic effort work on friday. when a lifter is really near the top of their genetic potential, they cant do 5 sets of 5 consistently with heavy weight. for example, i dont think kyle gulledge could do this. hes squatted 700lbs with belt and knee wraps, so i estimate his raw squat as around 625-650lbs, probably pretty close since he did a chain squat raw last week with about 650lbs total weight, with a lot of that weight taking the form of hanging plates attached to the chains that came off the ground all at once right at the sticking point, a very hard way to do it. its normal for a lifter to be able to do 5 sets of 5 with around 82-87% of thier max squat. 85% for kyle would be 550lbs or something like that. i dont think thats something he could benefit from doing week in and week out. hes almost superhuman, but to recover from this weekly and still be able to train other lifts would take a cape and tights, almost superhuman wouldnt cut it. so for a guy like this, we wouldnt use it all the time, we would do 5 sets of 5 with lighter weights for 3-4 weeks, working up to one really heavy workout trying to break our record, then move on to a more westside style of training, with max effort work one day and dynamic effort work another day, much easier to recover from if you are pushing really heavy weight.