A good book on pre-empts, Ron Andersen and Sabine Zenkel's Pre-empts from A to Z, agrees with Ross that pre-empts are more successful when partner knows what to expect from your pre-empt. If you open 4H in first seat and this can be anything from
x
KQxxxxxx
xxx
x
to
x
AKJxxx
Kxxx
xx
partner is never going to know what to do if opps bid 4S over your 4H.
Opening at the 4-level with an opening hand is not discussed in this book, as far as I recall, because the book is aimed at players who want to improve their game but know better than to do that.