Stevy Liakopoulou outlines six steps to optimize a large e-commerce sitemap:

1. Hierarchy + organization: Group URLs logically in the sitemap to reflect the website's navigation. Use sub-sitemaps based on product, categories, or topics, and create separate sitemaps for different languages.
2. Categories/subcategories with 0 or 1 product: Merge thin content pages with relevant categories or set a 301 redirect to appropriate categories and remove them from the sitemap.
3. Product pages with 0 content/duplicated content: Prioritize products by revenue importance, manually optimize high-revenue products with unique content, and consider no-indexing or gradual optimization for less important products.
4. Out-of-stock products: For permanently out-of-stock items, redirect to relevant products if they have traffic, backlinks, or revenue, or use a 410 status if they don't. For temporarily out-of-stock items, update schema markup and provide a 'Notify Me' option, keeping them in the sitemap.
5. Products with multiple variations: Identify the most popular variation, use it as the canonical tag for other variations, and only include this variation in the sitemap, while monitoring for changes in popularity.
6. Errors: Remove pages with 404 errors from the sitemap, correct redirection issues, address soft 404 pages by optimizing or redirecting as necessary.

Out-of-stock products should be treated based on whether they are permanently or temporarily out of stock:

• Permanently out-of-stock: If they generate traffic, have backlinks, or contribute to revenue, redirect them to relevant products with a 301 redirection, remove them from the sitemap and product feed. If they don't contribute to the business, set a 410 HTTP status and remove them entirely.

• Temporarily out-of-stock: Update the schema markup to reflect availability, create internal link blocks to other relevant products, provide a 'Notify Me' button for users to receive restock alerts, and keep these products in the sitemap.

For product pages with duplicated or no content, take the following actions:

• Identify which products are important for your business in terms of revenue.
• For important products, manually optimize each one by creating unique, compelling content, optimizing meta descriptions, adding FAQs, videos, unique images, updating schema markup, and possibly using AI for product descriptions.
• For less important products, either optimize them gradually after the important ones or add a no-index tag and remove them from the sitemap.

For products with multiple variations, such as a T-shirt in 20 different colors, follow these steps:

• Determine which variation generates the most traffic, has the most backlinks, or makes the most money.
• Set the most popular variation as the canonical tag for all other color variations.
• Include only the most popular variation in the sitemap and exclude the rest.
• Continuously analyze and audit to ensure the chosen variation remains the most popular, and update the sitemap and strategy as needed.