Surface Mail Experiment

With the impending price rise, the cost of sending a postcard abroad will go from 88p up to 97p for Europe and £1.28 to the rest of the world by "airmail" or International Standard. There has been talk amongst UK Postcrossers about sending postcards via surface mail (or, International Economy).  Current price for upto 20g to rest of the world is 78p and will rise to 81p.. a "considerable" saving. However, how long will the post take to reach the destination. Royal Mail, according to their website, aims to deliver surface mail to the USA within 28 days.... and I've had a look at other selected rest of the world countries and to them, RM's aim is within 56 days. So, I thought I would test it. On the 7th March, I posted in the postbox with 5 minutes to spare for the 5pm collection, letters (note, letters, not naked postcards), to people in: Canada - Ontario, Quebec, Saskatchewan, Nova Scotia; South Africa; USA - two people in TX, and one in MA, FL, IA, MI, and Hawaii; and one in Australia. 13 items in total. I didn't write "Surface Mail" on any.
May send another batch of surface mail stuff later in the month or next month and hopefully to other countries...