Yield to Maturity. The rate of return on a bond if it is held until maturity. This is expressed as an annual rate; the calculation of the YTM includes the coupon rate (if any), length of the bond, market value, and face value. Bond quotes are made in terms of the YTM, but an individual investor's yield may be different if he/she does not hold the bond, or if the bond is called before maturity.
Quick Answer. Jumbo shrimp are boiled for 7 to 8 minutes in salted water. Large shrimp are boiled for 5 to 7 minutes.
Armed with all of those (probably useless) variables, my anecdotal answer is that it should take around 15 to 20 minutes to bring six quarts of tap water (temperature) water to a full raging boil. I suspect you have a very low end stove and (possibly) stainless steel cookware. 50 to 70 minutes is far too long.