How can one optimize regex usage in the Rewrite engine to avoid multiple lines of code?

To optimize regex usage in the Rewrite engine and avoid multiple lines of code, you can combine multiple rewrite rules into a single rule using regex capture groups. This allows you to match different patterns and dynamically generate the rewritten URL in a more concise manner.

```php
RewriteEngine on
RewriteRule ^blog/([0-9]+)/(.*)$ /index.php?id=$1&slug=$2 [L]
```
In this example, the regex pattern `^blog/([0-9]+)/(.*)$` captures both the numeric ID and the slug from the URL, which are then used to construct the rewritten URL `/index.php?id=$1&slug=$2`. This single rule replaces the need for multiple separate rules for different URL patterns.