A double espresso from 16g of beans is less than 40ml and stronger than a bigger lungo from a nespresso pod (~7g coffee).
Smaller cups tend to be stronger. That same double espresso with 130g ice and 100ml milk and blend until ice is crushed makes a pretty strong frappuccino.
From espresso to lungo / americano to Starbucks recreations, they all basically use the same dose but wildly varying cup size.
Cup to mug of the same strength filter coffee makes a difference though.
Here's a link to a consumer review org that actually tested it with standardized loads and measured drying times. They don't work, takes just as long and cost the same in electricity.
https://www.choice.com.au/home-and-living/laundry-and-cleaning/dryers/articles/dryer-ball-review
It's sad that nowadays most "reviews" are just going by feelz and not by numbers. The placebo is strong with this category.