I have used this in the past with some success. If it's really bad I use the fine scrim as well. Takes ages to feather it all out to make it disappear with the scrim but my hallway skirtings have not cracked in 10 years and next door dug a basement and tore all the internal walls out about 7 years ago. Buy it from wherever, the links are just the first hits on google for me.
This is annoying to say, but how easy is it to push the skirt back to the wall (it will spring back to being out), but given it's throughout the house were they just tacked on
Fill the hole, scrim, cover the scrim with flexible filler. I use flexible filler to fill the hole too.
The flexible filler is noticeably more rubbery than mastic and has fibres in it. At least one of the options has fibres in, not sure if that's the one I linked to.
I have used this in the past with some success. If it's really bad I use the fine scrim as well. Takes ages to feather it all out to make it disappear with the scrim but my hallway skirtings have not cracked in 10 years and next door dug a basement and tore all the internal walls out about 7 years ago. Buy it from wherever, the links are just the first hits on google for me.
https://www.u-pro.co.uk/products/toupret-fill-flex-interior-and-exterior-filler?currency=GBP&variant=41430389227706&utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&utm_term=&utm_campaign=DG+Shopping+-+Toupret&utm_source=adwords&utm_medium=ppc&hsa_acc=1527711511&hsa_cam=17308313755&hsa_grp=142574308768&hsa_ad=599368186997&hsa_src=g&hsa_tgt=pla-1409556923658&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gclid=CjwKCAiApvebBhAvEiwAe7mHSLcOcdj3xn-mGyWJ4Ao8PFmz3KcM2Oy4LnTlQztMettCImNOWblIWxoCdaoQAvD_BwE
https://www.decoratingcentreonline.co.uk/toupret-ultra-fine-elastic-scrim-tape.html?gclid=CjwKCAiApvebBhAvEiwAe7mHSIqQETrab-CGMxu3IspEa8x4n2QOu71H5zgsS7_F02U_AnpS4cq-LRoCMqUQAvD_BwE