With relational, database-driven marketing databases becoming more common, most marketers can select RF&M scores independently.
The best customers would have a composite score of 15 (5+5+5) and the worst customers would have a minimum score of 3 (1+1+1). Many of the customers would have a score of 7 or 8 and it would be difficult to sort them.
Further, the experience of decades of direct mail marketing suggests that the most recent customers are of greater value than those who have ignored more than a few repeated mailings. To enhance this composite formula, many mailers multiply Rx3, Fx2 and Mx1.
This would give the best customers a composite score of 30 (5x3)+(5x2)+(5x1). This not only gives more power to the most Recent names, it also gives a bit of a boost to Frequency.
The logic behind weighting Frequency is that if two customers have equal Recency, spent the same amount but one ordered several times and the other only once, the more frequent buyer is much more likely to respond. If the choice were which one to mail your last catalogue to, the choice would be the more frequent buyer.
One additional enhancement is often employed in creating a composite score. Instead of multiplying by 3,2&1, substitute 9.9, 6.6 and 3.3. This yields a range of composite scores between 99 and 19.8. It preserves the approximately 3x weighting of R, it also creates more of a 100 point scale.