If I have a host with 30 items and I want all those items to be checked once from 8:00 - 9:00 every day and I want them to be spread as much as possible, I would basically had to open each item one by one and input the following custom intervals for these items:

item1 - h8m00
item2 - h8m02
item3 - h8m04
...

It's even a worse thing if I have the exact same item on a lot of hosts which I want to be run once within an hour but for Zabbix to spread them out, so not all items are run on all hosts at the same time. For that (if I have a template) I would have to modify the custom interval for each host separately.

It would be really useful if you could tell Zabbix to run an item at a random time from 8:00-9:00. I'm not sure what would be the syntax, but it could be somethig like:

h8m{random(59)}

or just specifing:

h8

This could also mean one time at 8 o'clock at any minute, and not what it currently means 8:00.

Zabbix could also make this scheduling smarter on the backend side. It could automatically take that random interval of multiple items and spread them acros the duration of the interval, so that the function isn't actually random, but smarter.