Oh, of course, I do use cron, I use it to run my renew script once a week. It's just that I use cron to run a script rather than run letsencrypt directly. My script reloads Postfix and Dovecot as well as Apache (I run my own mail server) and does a few other weekly housekeeping tasks related to certificates.
Having my certificate management in a separate script means I can run everything at once whenever I want, the script can be formatted in a very readable manner, and my crontab is tidier 