I do it about every 2 weeks and a series of full and flush. I have an MSR dromedary hydration bag-6L size-with the optional shower attachment that I have attached a nozzle to. MSR bags have food-grade poly interior and no harmful plastics like some shower bags do.
I take a series of 3 or 4 of those, but only 2L-3L at a time and then expel until clear. But a complete session is about 20-25 qts. total. Once cleared out, I can take about 4L max after fully empty, and it took 25 years to get to that capacity. For many years I was a 2-3 quart max., so everyone's colon is a different size, just like different penis and boob size--you work with what you got. But after many years, it did expand slightly to get another quart in. I always stop at pain, I just go for the pleasure and good feel, you know what I mean by good feel.