I have my portals on a shared hosting environment. The timer method depends on the application to be "alive" to function correctly, if the application is trashed due to saturation on the AppPool or due to inactivity, the timer method works oddly. If you use the request method, you depend on the visitors to trigger the event nevertheless in my case it was no problem because the portal had a lot of traffic.
On my previous post I mentioned that I checked for the last email sent date, this is because the scheduler process is not accurate in time, I mean if you set a scheduler item to run every "1 day" you cannot be sure of the exact time the process will run. Therefore I had to check every hour if the mails needed to be sent or not.
Greetings