You don't know when those would be used?

/timer -u 86400 1 /amsg My mIRC made it past the 1 day uptime, yeah!

/timer -U 86400 1 /amsg Wow, I managed to get Windows ME to run for 24 hours straight!

As for the -c, that is obvious, I said "I am on the channel" not "is the channel window open" just like ischan. Ischan only triggers if you are on the channel, not if the channel window exists.

Why would -d need an ON TIME event? There are 7 possibilities
/timer -d [sunday|monday|tuesday|wednesday|thursday|friday|saturday]