To quote your example:
echo "The time is now $time";

becomes

echo 'The time is now ',$time;
What happens when your straight-up text becomes:

The time's now

Do you need to double-single-quote the apostrophe? A la:

echo 'The time''s now ',$time;

Do you want to have to deal with that instead of (potentially):

echo "The time's now $time";

Again, I don't know PHP, so I'm not even sure this is an issue. Just pointing out something I thought of off the top of my head.