For one truck with a handful of brokers, the workload is manageable by hand: find a load, sign the rate confirmation, deliver, send the paperwork, wait for payment. Many owner-operators run this way for years.
The case for a TMS is not the driving — it is everything around it. Where a TMS earns its keep for a small operation is invoice accuracy and speed (billing the linehaul plus every accessorial, with the right documents attached), document capture (a photo of the BOL from the cab instead of a manila folder), and a clear picture of which lanes and brokers actually pay well after costs.
The trigger is usually one of three things: a second truck, a factoring or direct-bill relationship that needs clean invoices fast, or a stretch where unbilled accessorials and slow paperwork noticeably hurt cash flow. Below that, the honest answer is that a disciplined spreadsheet is enough.
Terms in this answer: Accessorial Charge, Lumper Fee, Proof of Delivery (POD)
In Trailflow: the driver app.