Correct, in fact on the old RDW rate they would only need to do about 45 shifts in the year to bank an extra £25k....Really? Maths isn't your strong point, is it? Why would somebody contracted to earn £50k+ pa for a 35 hour week need to work the same number of hours again, to earn only half the pay???
Given the figures quoted so far in this thread, you'd have to average little more than 1 RDW per week to get an extra £25k, and you wouldn't necessarily have to do a great deal of work on said rest day. Certainly not anywhere near requiring a 12 hour duty and only taking one day off per fortnight