This is from the book by Medium Lisa Williams:


Excerpt from Survival of the Soul -

(When you pass) You might think that you wouldn't want to return to the scene of your passing, but all souls are asked to watch and be part of that process for emotional healing. And because you are still tied to the Earth plane, chances are you are going to want to make that visit - particularly if you didn't get to say goodbye because your passing happened quickly or tragically.

You will be able to see your physical body, which of course, is now removed from your spirit. It is not unusual for those left behind to want you to show yourself to them in your earthly form.

Yet it can be exhausting to make an appearance in the flesh, as it takes an incredible amount of energy to do so. Also there is no good time for you to do it. Even though they may see you, it will be such a shock that they might turn away and by the time they did a double take, you'd be gone, disappearing right in front of their eyes.

This could evoke emotions of regret that are intensified by grief - so for these reasons, such appearances are very rare.

Ariel gives more detail about this (channeled from spirit)

We who have passed have to use an enormous amount of energy to show ourselves physically. It is much easier to influence those on Earth to listen to certain songs, signaling them to trun on the radio when they usually would not. Then we can put a thought in through their guide to get them to listen at a certain time to a recording or a show. But for us to stand "revealed" before them is what people want most of all, and it is not as easy as you would think. Our energy level is so much higher than theirs because the Afterlife exists at a higher frequency.

In our dimension we have to work hard at lowering our vibrations to match theirs. It takes a while to master it at all.