This is more or less the same technique I use.
As long as it isn’t too wet in the bag, or isn’t too cold or hot, or it doesn’t get held up for 10 days in shipping, they arrive safe and healthy 9/10 times.
Right now is perfect shipping time in most of the USA. Fall too. Summer and winter not so good.
I find simple priority mail to be adequate, no need for the expense of overnight. 3 days is good. Costs about $8.