Let's look at what happens if we boost response in Month = 01, Month = 02, Month = 03 ... by 10% ... via a Welcome Program that goes after brand new customers right after they were acquired.
You boost response, and over time you have a better cumulative repurchase rate.
Now, let's bump response by 10% at Month = 15, Month = 16, and Month = 17.
Here, you multiply 10% gains against response figures that are close to zero ... giving you close to zero benefit.
We work so darn hard to "reactivate lapsed buyers". A lot of hard work. But the hard work doesn't translate into a meaningful difference ... because the customer simply isn't responsive anymore.
We need to act sooner ... sooner instead of later. When the customer is acquired, we need to act immediately ... just like we do when a loyal customer buys from the 7th time ... we jump all over that opportunity.
Focus on a customer who bought for the first time, and get that customer to buy for a second time quickly while the customer is still responsive.