When I set a route up for someone else to carry I'm always incredibly aggressive in how I notify the carrier of parcels. From experience I know that digging through a bunch of post that hasn't been marked in any way on a route I've never carried is probably the biggest waste of time you can encounter aside from flat-out getting lost.

On the post itself I will mark the tier of the delivery on the case. If it's very heavy post I will mark whether it's on the left half of the case or the right (all cases at my station are five tiers with just two wings). So a package right at the beginning will have 1a on it and at the very end it will have 5b. This allows them to load the vehicle very efficiently.

In the mailstream itself I will also mark the post. On a park and loop route I will case a piece of scratch paper at the beginning of a split with the addresses of any packages that are on that split. If it's mounted I will case a piece of scratch paper with the address at the front of the cell for that delivery. If it's heavy post or someone new, I will even denote the size of the package with a S M or L. So if there's a large parcel at 500 Main street they will have a piece of scratch paper with "500L" on it before the split.

This is a bit extreme I know but I'm pretty quick at throwing mail and have never spent an inordinate amount of office time making sure the person carrying off me has a good day. As a CCA myself I know just how much stress a garbage setup can create. With all the other bullshit that can happen out there at least I know they will not have problems finding their post.

As for carrying my own stuff, it depends heavily on the route. The one thing I do use consistently are tubs though. I like to have small tubs filled with small post in order. I still mark my packages aggressively on mounted routes. When the post is heavy, I just tend to believe that you waste less time in the office getting very organized than you'd waste constantly checking if you have a package coming up on the street.