What is more efficient and/or what is better practice, to echo the HTML or have many open and close php tags?
php
Obviously for big areas of HTML it is sensible
Whichever makes sense to you. The performance difference is marginal, even if a large echo is faster.
But an echo of a big string is hard to read and more <?php echo $this->that; ?> tell a story :)
<?php echo $this->that; ?>