If you are next to the computer, and if it’s switched on, and not gone to screen saver, etc. (and are super fast).
Whilst I do have a guitar near my PC, I rarely use it. I mostly practice in another room and have to find my laptop and a power cable and set it up if I want to use it there. That often means I have to boot it up or, at least, wake it up from a sleep state, log in, possibly deal with updates, and try to not get distracted with email and chat alerts, load the application and select the patches I want.
That’s “only” a few minutes in reality, but that’s a few minutes more than turning on the power to my amp or modeller and waiting for the 1-2 seconds for it to start, and it is a barrier to getting into the mindset for practicing. If I had to do it every time I practice, rather than the handful of times I want to use a laptop for recording or Tutorials, I would practice a lot less.
I suspect many other people are in a similar position to me.
YMMV
YOU may not. I certainly can!
In listening tests I did recently, with rounds of computer simulated bells rung evenly 250ms apart, I can tell when around 10ms of error is added between two of the bells
And most people can hear, or “feel” 30ms of latency. 30ms was considered to be the maximum latency you can expect people to experience on a phone call before it starts to becomes difficult to talk without echo cancellation.
On a guitar, I feel the slight lag between picking and the sound coming out. It is very tiny, and it won’t bother most people, and it’s a feeling rather than a plainly audible thing. But it is noticeable if the latency is higher, even if it’s perfectly usable. Especially when using headphones.
Cheers,
Keith