I used to subscribe to S&T too. They do come late occasionally but during my subscription period of 2-3 years, I did not lose any issue. Instead I got extra copies because when it failed to arrive after 3 weeks, I feedback and they sent me a copy but I received 2 copies instead. (one replacement and one late issue...haha). Gave the extra issue away.
Now i only subscribe to Astronomy, not because I don't like S&T but just lazy to make the effort...haha. Whenever I needed to buy it, I get it from Kinokuniya. But of course, the discount from the subcription copy is much better.
The Boldly Go Where No Meade Has Gone Before
Captain, RSS Enterprise NCC1701R
United Federation of the Planets