They definitely don't sell 1,000 McFlurries a day. Assuming they fulfill one order every 30 seconds, and McFlurries are reasonably purchased between noon and midnight (never heard of a breakfast McFlurry). That's 1,440 orders per day. McFlurries are not going to have a 70% attach rate.

I live in South East Asia where there's fewer McDonalds restaurants, but they're much larger and higher volume than I've seen elsewhere (Europe, most of US and Australia). The ice cream machines often sit at the front of the restaurant (since many restaurants are located in malls). Many people pass by and buy ice cream only. But you can still order them with your regular menu from inside the restaurant. They sell a LOT of ice cream here.

Cones appear to sell more than McFlurries here.

Yeah, but then you have a family that orders 4

If any location is getting to 1,000 McFlurries then all I have to say is... America.

Assuming spherical customers in a vacuum...

McDonalds serves around 68 million customers per day (https://findanyanswer.com/how-many-customers-does-mcdonalds-...)

in around 39 000 restaurants (https://www.statista.com/statistics/219454/mcdonalds-restaur...)

Of those restaurants, around 9% have broken ice cream machines (https://as.nyu.edu/content/dam/nyu-as/psychology/documents/c...), meaning there are around 61.88 million customers who had the opportunity to order a McFlurry.

I wasn't able to find good data on what percentage of customers order a McFlurry, but the linked article says they make 60% of dessert sales. I'm going to make a wild guess at this point that 50% of customers order a dessert of some description.

That means about 34 million people ordered a dessert, about 20 million McFlurries and 10 million other desserts.

Of those people, 3 million were not able to order a McFlurry because the machine was broken, so let's remove those 3 million from the total.

31 million people, 20 million McFlurries.

Assumption then would be that on average, around 1/3 of customers will order a McFlurry in a random restaurant (50% x 66%).

68 million customers across 39 000 restaurants is around 1 700 customers per restaurant per day, of which around 570 will order a McFlurry.

A regular McFlurry costs $2.39 (https://www.fastfoodmenuprices.com/mcdonalds-prices/), so a restaurant takes around $1 350 from selling McFlurries.

Taylor have a helpful calculator on their website (https://taylornewengland.com/sales/soft-serve-ice-cream-prof...), with likely optimistic estimates and don't show any wastage, but we're ballparking anyway. They say that food cost + napkin + cone comes to around $0.29, meaning daily profit from ice cream would be around $1 200.

Conclusion, it's pretty unlikely the difference is on the 'orders of magnitude' scale.

As a side note, given that the cost of a new machine is around $18 000 (https://www.wired.com/story/they-hacked-mcdonalds-ice-cream-...), after 15 days of the machine being out of order, the cost in lost sales is as much as buying a new machine (lower by whatever the Taylor callout fee is).

Given that 9% of 365 is around 33 (more than double the cost of a new machine), it seems that the more cost-effective solution would probably be to have a second, standby machine, from which McFlurries could be served while waiting for the callout.