My cart is set up so I can do 80-90% of my daily work without going to my main toolbox. Most of what I've got in the cart is duplicated to some extent in the main box, but it's not really a set of "duplicate tools" per se. The majority of what I work on is metric, so the standard tools stay in the box until I need them.
Parts go on the side shelf if they fit, otherwise they go on a workbench, or a dedicated parts cart.
Take a look:
Top of cart contains sockets and ratchets in the main area. Sets are 1/4" deep sockets, 1/4" wobbles in the five most needed sizes, 3/8" shallow impact, 3/8" wobble impact, 3/8" deep impact, 1/2" wobble impact, 1/2" deep impact. Six or so different ratchets in assorted sizes. Also have gloves, a couple different types of markers/pens, P/S hose cutter, carbon scraper, flat bladed putty knife, cordless impact, cordless screwdriver, cordless worklight, hood prop, square plug wrench for differentials, mirror, magnetic retriever.
On the left side: Prybars, extensions, radiator picks (not just for hoses), wire grommet tools.
On the right side: Nutdrivers in 1/4", 5/16", 3/8" (for hose clamps and switches), 8mm battery terminal wrench, 1/4" handled extension, 25" straight screwdriver (for winterizations), Serpentine belt routing tool, bent prybar for brakes, straight bladed prybar with striking cap.
Drawer contains disconnect tools, refractometer, IR temp gun, hose clamp tools, headlamp, filter wrenches, brake lining gauges, door buzzer sanity tool, tire pressure gauge, you know.. general service type stuff.
Electrical diagnostic and wiring tools. I've since moved my Teslite leads from my Fluke meter to the Vantage because I use it far more often than the Fluke.
Ratchet wrenches, stubby wrenches, long pattern wrenches, assorted pliers, paramedic shears, etc. The assortment of pliers seems to vary according to what I've been doing.
Hammers, impacts, air ratchets, serpentine belt tool, air chuck, allen key sets, UV dye, etc. are the standard items in this drawer, but additional contents vary wildly depending on what I've been doing.
The bottom of the cart usually has a tacklebox with electrical connectors in it, a couple of spools of assorted primary wire (I do a lot of wiring), common aerosols, brake caliper compressors, etc. kicking around in it.
At the end of the day my cart usually ends up looking like this: