It depends on what you have selected in the "Navigation" tab of the galaxy map. By default, the "economical routes" checkbox is checked. This shows you connections that consume less fuel, but might need more jumps to get to your final destination when you select "plot route".
If however you select the "fastest routes" checkbox, then all routes are recalculated and will show the fastest way to get somewhere (your FSD range also matters, of course).
Note that all these routes are for the "plot route" function. If you select any system, you can just jump directly to it if it's within the current maximum range of your FSD (which changes depending on your current mass, like when you have cargo or heavy ship modules.)
So no. You are not restricted by these lanes on the map. You are only restricted by the capabilities of your FSD
