If you are trying to create a new habit or trying to use a mobile app more regularly, you would obviously have better luck if you placed the app on the Favourites row. It could be a planner app, an e-book reader, a food-tracking or exercise app, or whatever else.
But it is possible that row is limited and filled with other important apps like the caller app, browser, camera, etc.
So in case you use a page-type layout for apps, the next best option after the Favourites row, is to place that important app in the row just above the Favourites row or in the top row. Because either of these is where your general gaze goes to each time you look at your phone.
If you use a Menu layout with apps (or app folders) on a vertically-scrolled grid, you might be better off placing the important app in the absolute middle row, or the topmost or lowest row.
When you use your phone the next few times, observe which section (top, or lower) of the phone you pay attention to.
Or without checking on your phone, try to think of one or more apps that you think are on the top and bottom (one above Favourites) row on your phone. Placing the important app in that row will remind you to use that app more regularly.
If you aren’t in the habit of rearranging the layout of apps on your phone, key apps that you believe might help you improve on some front, will have a greater tendency to remain downloaded but forgotten or seldom used.
Questions and thoughts welcome.