My personal opinion is that placing landing legs on a stack of blocks is dangerous. It the event of a windstorm or other force that shoves your trailer, the legs could be pushed off the blocks and result in damage to your trailer. Of course, the windstorm or other force might hurt something, too.
On soft ground, I will use a 1x2 block.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch