I've been collecting them since the start and have not had any problems opening the PDF files. Just went to check on today's to make sure. Nice thing about this site is you can go back to download any you missed as sometimes I forget to go to their site daily. I keep a folder on my PC for "daily DL", "weekly DL" and of course "monthly DL". Plus I have a printed sheet for any collections of embroidery designs I'm saving so hopefully I don't miss any in the collection. From time to time I do miss them and have to hope they will put them out again for free.
Here's the website for anyone interested................
www.365challenge.com.au/the-blocks/