Emails are not unreliable, especially if you have your settings correct. You can set most emails, except POP and IMAP to push and get them almost immediately. However, if you are trying to run POP through outlook.com or gmail, it will only come in whenever those sites go out and get your pop mail. For example, if you have
user@outlook.com, and someone sends you an email, it will come in immediately. If you have
user@comcast.net set up as a linked account in outlook.com, outlook may only check for new pop messages every 20 minutes (can vary). When it finds one, it will pull it in and then you will get it on your phone.
As far as notifications on the other apps, some are good and some are bad.