Little mantra in my head whenever I'm doing anything...
Titan HM as DPS ->
Stack, Break, Stack, Break, North Edge -> Jump
Break, Stack, Break, Stack, Break, Stack, North Edge -> Jump
Break, Stack, Break, Marker, Break, Stack, Break, Gaol, Stack, Break, Stack, Break, Safe Zones, North Edge -> Jump
Break, Heart, Gaol, Break, Limit, Heart, Stack, Break, Gaol, Stack -> Earthen Fury
Stack, Break, Front/Back/Left/Right/Marker/Safe Zones + Lure, Break, Gaol, Stack, Break, Repeat until Finished.
Everyone eventually learns or partially picks up a similar understanding; if they don't they likely have a hard time getting through the fight - ie. eating a plume, eating a bomb, flying off
It varies slightly - Healer and Tank have to additionally remember "Mountain Buster" in the final phase mantra. Healers learn to time their Medica II right as Tumult start, and how to precast Medica on Jumps and begin moving to avoid plumes, Tanks learn how to stretch their CDs and prepare for Buster etc.
If you've got a voice chat and someone with a good memory they can just recite what's coming next so people can prepare - this is how our Australian friends started getting through the endgame content.
Grouping in FFXIV boils down to memory and meeting gear checks; everyone demands experience - they want you to know the pattern, be able to recall it accurately, and execute accordingly. This demand is usually accompanied by gear requirements - people are human and they can't maintain a perfect repetition indefinitely; we break down, we make mistakes, we lose focus, or our dexterity suffers - this is why many fights seem impossible in lower item level gear.
The last factor in grouping is latency; connection to the server is vital. If your connection is unreliable you are, by extension, unreliable.
^ FFXIV and FFXIV's community have several draw backs; and with the vehicle of Duty Finder/Instanced content coupled with this style of content it quickly breeds a hostile environment.
Personally: I enjoy playing FFXIV with people I know; something I feel developers continually discourage by using excessive reward and content lockouts, limited social interaction within your server, and almost no content geared toward large groups (Free Companies & Linkshells) that is not cosmetic (Housing) or badly implemented (FATE),
I don't include Crystal Tower yet because I am holding onto the hope that we will, someday, be able to queue with a 24-man pre-made Free Company Alliance.