Front derailleur cable keeps snapping, change of riding habits perhaps?
Excessive force or frequency in front shifting habits may be able to play a role in a cable breaking, but it's very likely that it was primarily caused by factors beyond your control.

Front derailleurs vary in how much bending in the cable at the anchor bolt is created as they move through their range of motion. Some recent mountain front derailleurs push this to extremes, which is unfortunate because in doing so they add to the risk of breaking cables.

Mechanics are at times faced with a decision in setting up cables whether to accept there being a previously anchored section between the final anchor point and the lever, or of clamping partway over a previously anchored spot. This can happen as a result of anchoring the cable and then the derailleur's mounting position needing adjustment or by needing to have less starting tension or a more inbound low limit screw adjustment. The problem with allowing this is that it creates some degree of a weak point, and whether it's enough to lead to breakage is impossible to say conclusively. Typically the more skilled a mechanic is, the better they are at sticking to an order of operations that negates this, while newer mechanics may not even realize it's something they should care about. 

At some point, the scrupulous decision becomes to put a new cable in and start over, but it doesn't always happen when it should. When cables break at the anchor bolt, I think this is the most common primary reason.

As for shifting habits, most people on multiple-chainringed modern bikes (as opposed to 10 or 12-speeds, say) stick to choosing a chainring that matches the current terrain and then adjusting their rear gear as needed. So in other words you're shifting in back far more frequently than in front. Because the jumps between gears in back on modern bikes are relatively small, not much is lost with this approach in terms of pedaling efficiency, and the inefficiency and hassle of doing all that front shifting is saved. Older bike drivetrains with smaller numbers of gears in back and larger jumps pushed one more in the direction of making constant front shifts in order to find a reasonable gear to be in.

There are stylistic and strategic elements to shifting too. Some people just like using muscle to get through spots where a lower gear could also be appropriate, or conversely might choose to force themselves to operate at a higher cadence when a higher gear would also work. From an efficiency standpoint, these things have to be weighed against the lost efficiency of bothering to shift, especially in front.