Grant full permissions by default on Ubuntu

"No. Files by default will not receive execute permissions no matter what the umask is. This is a security feature. If you want any files to have execute permissions you will have to explicitly set that with chmod.

666 is

rw-rw-rw-

as you can see the x bit is missing from the owner, group, and other's permissions (which is worth 1).

directories can receive 777 with a 000 umask because executing a directory allows you to change into it. This doesn't impose a security risk like executing files (scripts, binaries, etc)."