I have been using polycel One Fill for many years now and had many disapproving looks from my peers. But hear me out; ready mixed its hugely convenient, not bad value if bought in 4 litre tub, no waste with throwing away leftover filla, great for big bits of making good around sockets etc, lite enough to hang in on a big cieling hole, really easy to rub down, great for filling in any open seams on lining paper. But for me the major thing is unlike conventional powder fillers it has some give in it and it would seam that that quality allows it to tolerate some movement when used on cracks that might move.
Many years ago I did an experiment at home after having upvc windows fitted there was some making good to do on the internal reveals.So i made good with Red Devil One time…and some 10 years later it has held up exceptionaly well. Ok so this is where it gets a little less scientific because I am talking two different products. I didn’t really like some of the red devil qualities but found the One fill similar but nicer to use.
Any way my theory is that it will tolerate more movement than more brittle powder fillers.
Having said all that, it has its limitations, not great over shiny surfaces, will flash through needing maybe 3 coats to cover. And I wouldn’t use it where there is considerable amounts of filling to do that require caulking out.
That’s my 2 pennies.