Variable sync technology is meant for cases where you go below native monitor refresh rates.
At 144Hz, your display is drawing a frame every 6.9ms.
Without vsync, your display starts drawing whatever is in the framebuffer every 6.9ms. As the framebuffer can be written to much faster than the display refresh setup, this is why you see tearing, as you are seeing part of one frame, and then the rest of the next. As long as you can consistently maintain high frame rates, you will probably notice this less. IF the framebuffer is NOT updated, you still start drawing whatever is there. If the GPU can;t assemble a frame for say 15ms, (longer than 6.9 + 6.9 for two individual frames) then you will have that torn frame displayed for 2 full display cycles, keeping it on screen. This is only for a fraction of a second, but noticeable to some people
With Vsync, your display draws a frame every 6.9ms, but cooperates with the GPU to only draw FULL frames. As long as your GPU has a frame ready to go in under the frametime, then variable sync doesnt come into play. If you miss that 6.9ms window however, the monitor will have to display the completed full frame another 6.9ms until the next draw cycle. It doenst matter if you JUST missed it (say you had the frame ready to go at 7.1ms), you are stuck at fixed refresh rate cycles. This evveftively halves your framerate for a split second if you miss 1 fgrame, ivides it in third if you miss two frames, etc. This split second effect people notice as stuttering.
Variable sync comes in to play at longer-than-native refresh rate times because you don't have to wait for that fixed 6.9ms window. If you exceed the nominal refresh rate (6.9ms for 144Hz), the GPU and monitor working together can interrupt that cycle and start drawing now when the frame is ready, instead of waiting the additional full refresh time. It doesnt matter if the frame is ready in 7.1ms, 9.2ms, 15.8ms, etc. The display can draw the frame now. This helps reduce apparent stutter.
If you NEVER drop below native refresh rate, even for 10%, 1%, etc low frame times, then the technology won't offer you anything. If you do have dips below that for a fraction of a second, then it depends on your individual tolerance to the microstutter, and how low those dips are. Variable sync helps smooth those dips.
This is dependent on your variable refresh compensation technology as well. Some Freesync panels have some pretty narrow compensation ranges. Gsync tends to have wider compensation ranges available.