As PVP games become more dynamic, players are required faster reactions and then lagswitches become more effective if you can activate it quickly.
I understand that it's way simpler for ordinary players to just build a physical lagswitch like this:
But I think it's an annoyance to keep removing hands from the keyboard to stop the incoming traffic then again to resume.
A more advanced approach that allows much faster reactions and even more customization is by using a virtual machine like with VMWare, install Linux and use netem. Network traffic is rerouted to the virtual machine and with autoit you can send keystrokes to the virtual machine to run scripts or even plain tc commands.
It's also undetectable by client application scanning and only when one really goes overboard by abusing it that it can lead to questionable sanctions.