This is why systemd gives you the RandomizedDelaySec option. (Other cron-like facilities may have similar features, I'm not discussing them here). Set that to N and each time the timer reaches its trigger (say, once per day), its actual start will be up to N seconds after the trigger. E.g. if a once-per-day trigger is at midnight but you have RandomizedDelaySec=300 set, then it will run sometime between 0:00:00 and 0:05:00, with a different actual start time each day.

If enough people used that, with a high enough value of N (say 1800 for jobs that really don't have to start at any particular time), it would greatly spread out the spikes in accidentally-coordinated usage.