As the other responses have said, burning at 1x with modern high-speed DVD-R media will greatly increase, not decrease, the odds of getting a coaster (unreadable/unplayable disc). This is because the PIFs (Parity Inner Failures) and POFs (Parity Outer Failures) will increase dramatically with slower writing speeds, especially on burners whose write strategies don't properly implement slow-speed writing.
On the other hand, if you've been getting DVD-R's which become unplayable on standalone DVD players when burned at the higher speeds that such media is designed for, either you have crappy media or your burner does not properly support this media (in terms of write strategy).
By the way, I had TDK DVD-R media (MIT) rated at 8x - and it did not burn well at its rated speed (the write speed was forced to drop to 4x in order to complete the burn). This lead me to believe that this media is lacking in quality control.