Strimmer

You get a strimmer with a self feeding line head. You fill the head up with line and then when it wears down you tap the head on the grass (soft surface NOT hard) and more line gets feed out. I use this one https://www.amazon.co.uk/gp/product/B00L476FA2/

btw if you are "fixing" the wire that often you are either using it wrong or using the line on material it isn't meant for. I used to have a manual feed head and it was annoying to have to keep stopping but I could go for a good length of time in between feeding more line. Anything under 2.4mm won't last long on brambles unless the line is made for that job. If your strimmer is powerful enough then this 3mm line works well in really tough conditions with a lot of stones and brambles https://www.amazon.co.uk/gp/product/B006E1D20O/

Its a bit more complicated than that. It used to be like that with some older strimmer heads because the eyelets the line comes out of used to force the line at a sharp angle when it came up against anything it was slow to cut through. Most newer heads like the one I linked to have much wider arcs on the eyelets so that doesn't happen as much. Another major factor is heat. There is a whole lot of friction going on when the line is cutting so the line gets quite hot, combine that with a poorly designed eyelet and over aggressive use and the line will be snapping every 10 seconds ;-0 The line I linked to seems to work at higher temperatures so rarely breaks even on brambles.

Thickness of line is also a factor. My wifes little battery strimmer has 2mm line and it can't touch anything that isn't easy to cut like grass and it doesn't have enough power for anything thicker. My commercial brushcutter is happy with 3mm line which has more than twice the amount of plastic in it and consequently doesn't wear as fast.

If overheating is the issue you can easily spot that when you pull new line out as there will be a round notch melted into the line where it was rubbing against the eyelet.