This will vary by the type of Folio.

StickyAlbums: We recommend having not more than 20-40 images. Note: If offline cahcing is enabled, you won't be able to have more than 40 images in your Album and have it save for offline viewing. You can add more, but this feature will not work.

Marketing Folios (all other template styles). We recommend showcasing your best 15-20 images in StickyFolios marketing sites. StickyFolios are designed to load quickly. However, the more images you feature on the site, the slower your Folios will load.

Rather than presenting all your favorite images, you can rotate them and update your site frequently to keep your site content fresh.