Meaning of cada tercer día by Cesar Orozco

I'm English teacher and a student, and I, we will encounter this problem. The issue of the use of this rare er concept, the common criterion is the following: what must be is made until the third day. I.e., if they now prescribe you a medication, you take it today and reopen it to take on the third day. Today Monday prescribe it to you and return it to you to take on Wednesday. They really are after 48 hours but they are three days, Monday, Tuesday, Wednesday. Wednesday restarts the count and that day as the first account, now would be Wednesday, Thursday and Friday. Monday Yes, Tuesday, Wednesday if Thursday, Friday Yes. I know that it is a concept wrong logic, but someone (we don't know who) decided to popularize the phrase of "a day and a day not", therein of "every other day". It is important to understand what refers the person who tells you because while you could be taking you a drug 3 times a week you end up tomandotelo two by the concept of every 72 hours. I recommend that you investigate the person to which you are referring, only here I explain what most people understand by "every other day".