I always use the bonus on the RP promo periods, so like on the last weekend it was 5RP promo, I usually just like to do portions. This time I didn't have much time so I only claimed 50k sats.
I see it as more like x50 wager though (because it is x25 of bonus claimed + your equal amount). so if I claim 50k sats I have to wager 2.5m sats or 25 mbtc.
Usually I do more like 100 mbtc wager (claiming 200k sats).
Now I still have almost 6 mbtc in bonus waiting to be claimed. Slowly but surely

That is a good strategy to play only on promo periods and using only the last 2 top prize x4 and x5 RP for every 500 satoshi wagered,the more the amount we wager the better the amount of side benefits as it is a sure thing that with that house edge we will lose all of our balance sooner or later depending on the amount of our bet.
0.006 Bitcoin to be played here in the multiply game at x4 or x5 RP means you are going to get at least x10-x20 that amount wagered and that is 0.06 to 0.12 Bitcoin in wagered amount which gives you great great benefits.
I mean if you are after a "strategy" then I agree that it is a good strategy, but at the same time if we are talking about having fun, then this sucks the fun right out of everything and I honestly hope that it doesn't get there.
I believe that you should always gamble the way you want to gamble and can have the most fun, if this is the way you will have the most fun then you should do that, but that doesn't mean that you should do it because it would be efficient and you would not have fun but you would have the highest chance of making money. That means you are doing something you do not want to do, not having fun, and probably still not making any profit as well, none of those makes any sense to me at all and should be avoided. Only valid advice if it is fun for you.