I've found some time savers I'd like to share. Because it's Tuesday right now I'll start with the Star Path.
In between Star Paths I leave all my memories and night thorns on the ground. When a duty is given to collect those it's extremely fast to gather them up. While the Star Path is ongoing I do not collect achievement dreamlight. When I get a collect dreamlight task then I turn in only as much as I need. On Tuesday I make sure all my royal task duties are completed in every dlc but again don't claim. Wednesday after reset I can check my new weekly duties and bang them out quick.
When grinding for dreamlight or the Star Path it's best to stack your duties. Leave cooking, mining, fishing tasks until you get multiple duties for them. An great example of this is Serve one meal in the Restaurant + Cook one meal 3 Stars or higher + Cook one meal 5 Stars or higher. If you goto the restaurant and cook the 5 Star meal request that completes all three duties. Serroh has a great video on YouTube about setting up for grinding I highly recommend.
In each DLC and the Valley I have collected all my fruit trees/bushes into an orchard and close by is Walle's Garden with a large chest by each. The stalls are grouped together by Scrooge's Shop with a chest at the last one. Both the boat and the Greenhouse have their own chests. In the morning before work I can feed all my critters (I'm still trying to get to 90) and hit all my shops, orchards, and gardens in less than an hour.
I have favorited Daisy's Wardrobe in my Furniture menu and use it to store Quest items, Critter feed, and Meals. If I need something I pop it on the ground, grab it and then promptly pick it back up again.
To change out companions quick I use the presets in the wardrobe menu. I have one for each tool with corresponding companions. Just a few clicks and my companions are right for the task at hand. Its also easy to edit them to highlight a new favorite. I just got R2D2 today's so my mining preset is changing right quick.
There are some settings in game that save you time. When cooking there is a toggle in the bottom right corner that turns off animation unless its a new recipe discovered. Huge time saver not to have Remi celebrate each dish. In Settings under Gameplay are two toggles I reccomend. The first being Hold to Complete Fishing, and Hold to Complete Timebending. Much easier.
Loading screens are the biggest time wasters of all thats why I love using the Plaza Floating Island as a Storage Island. Just one loading screen. Right where I zone in I have a sorting station set up. Once I have completed a stack they are pulled out of the sorting chests and put into long term storage. I have 3 Slow Cookers and all my crafting stations here. Everything is kept here except my crop chests those are on my Gardening Floating Island. I also have an pumpkin Island cause gardening is my favorite way to level.
Lastly if you have Remi's Delivery Quest tracked then travel to your Floating island to cook it ports the delivery requester to the Floating island and Remi to hand in. No searching someone out.
I hope this is helpful and please let me know your timesavers.