Every Customer Buys on a Different Schedule. Your Emails Should Too.

Last week we covered targeting a monthly newsletter by segment and purchase history. This week we look at optimising when that email goes out.

The problem with sending on a fixed cadence

A fixed monthly schedule treats every customer as if they buy to the same rhythm. A customer who typically purchases every three weeks is overdue well before your next scheduled send even goes out. One who takes six months between orders isn’t ready yet, and an email nudging them to buy again lands too early to mean anything.

One send date can’t serve both of these customers because it isn’t considering them as individuals.

The fix: everyone gets their own send schedule

Instead of one send date for the whole list, calculate each customer’s typical gap between orders, their personal median, then send their nudge when they’ve gone meaningfully past it, rather than waiting for the next scheduled email.

Three customers, three different patterns:

A single monthly send would completely miss Amira, she’s overdue by more than 70% of her normal gap, but the next scheduled email might still be weeks away. It would also wrongly nudge Priya, who’s right on schedule for someone who buys twice a year.

There’s no universal rule for how far past someone’s personal median counts as due but a reasonable starting point is 30-50%. A consumables business will want a tighter threshold than one selling considered, infrequent purchases, the cost of a slightly early nudge is much lower than the cost of a late one.

When personal timing doesn’t work well

New or single purchase customers. A personal median needs at least two or three orders to mean anything. Below that, fall back to a category average gap.

Irregular buyers. Some customers don’t have a real pattern, their gaps bounce around. For these, treat the flag as a softer signal, not an automatic send.

Mixed product types. A customer buying both a consumable and a durable will have two very different cadences. Calculate the median per category rather than across their whole order history, blending different category cadences produces something that doesn’t represent either.

Combining timing with segments and purchase history

We previously covered segment deciding tone and offer, purchase history deciding the content. Personal timing is the third piece, deciding when that email goes out.

A Champion who crosses their personal threshold still gets the early access. An At Risk customer who crosses theirs still gets the incentive. What changes is that these sends now happen the week it’s relevant to the recipient, rather than whenever the next scheduled newsletter lands.

What to do with this

Don’t try to build personal timing for your whole list at once. Start with whichever segment is most valuable to catch early, Loyal Customers or Potential Loyalists are usually the best fit, since a well timed nudge to someone already inclined to buy again converts far better than reaching them either too early or too late.

This only works if it’s running automatically, checking who’s crossed their threshold isn’t something to do by hand each week. If you’d like this built into what’s already been set up for segment and content targeting, that’s a conversation we’d like to have with you.