When I was at the law firm, I used tasks extensively and had a wait bin where I put things I was waiting on. I had a lot of trigger dates I needed to remember such as when to file a statement of defence after receiving a statement of claim, or putting in a reminder when the mandatory mediation kicked in. It was important that I pay close attention to my task reminders as these dates were critical to the lawyers I worked for. I had a few mediation and arbitrations to set up and telephone calls to schedule with clients, but the bulk of my work was preparing documents on time and reminding the lawyers I worked for what needed to be done and by when. I can count on one hand the amount of travel I arranged for them in the 15 years I worked there as their meetings were usually local meetings with clients or short flights to nearby cities such as Toronto, which is only an hour's flight and rarely required an overnight stay.
When I started work as an EA to the CEO and Corporate Secretary of the Board of Directors of a non-profit organization , that didn't work as well for me so I had to adapt and use other methods such as meeting sheets. I had so many meetings to keep track of that I needed a method of finding the details quickly from the various emails I had about the meeting. The CEO also was a frequent traveller to cities near and far. I became very familiar with time zones and making travel arrangements. I started a travel sheet so I could remember all of the things that needed to be done, especially for international travel. I very rarely needed to use task reminders, but did use them on occasion. Colour coded file folders also became very important. I managed a Senior Leadership Team meeting as well as the Board of Directors' and all of its Committee meetings. Having different coloured file folders, certainly made it easier knowing which folder went with which meeting.
Now that I am working in a hospital, I am back to using tasks again and as soon as I get around to putting in a supply order, I will order a tray to put things in that I am waiting on. I also use a stackable file tray and put folders in for the two meetings I organize. Nothing as extensive as I used at the last organization, but it is still handy to have these meeting folders on hand. I don't need colour coding though as I only have two meetings to manage.
I have found there isn’t a cookie cutter way of doing things. What works for one office, may not work as well for another. Or maybe you will use a combination of things that you have used in various offices. But don't limit yourself to only the things you have used before. I find listening and learning from my co-workers is a great way to learn new techniques. If they have been in the job for a long time, I listen even closer.