Degeiko is composed of two words, “De” and “Keiko”.
Keiko is quite familiar to you, I think. It means “training” or “practice”, right?
What do you think “De” means? “De” means "out".
So when we put "de" and "keiko" together, it becomes "training at somewhere other than our own dojo".
For example, I sometimes go to another dojo to train with people at their dojo. It is an "away" training for me, if training at my dojo is a "home" training.
So if you do not go anywhere and train with other kendoists from other dojo at your dojo, it is not "de-geiko" for you. It is a de-geiko for those who came to your dojo.
When we train with the same people all the time, we start getting to know strengths and weaknesses of each member. And we get used to each other's kendo and there will be no stimulation.
The worst case scenario is that some members get bored and leave the dojo for good.
This is certainly what we should avoid...
The main purpose of kendo is to improve ourselves. If we go and train at someone else's dojo, there will be many disadvantages.
When we train at someone else’s dojo, we are not used to it.
The floor could be too slippery or too hard. You could trip over easily.
You could feel differently in someone else's dojo.
Simply it is challenging.
And you may encounter someone you have never fought before and his/her kendo may be completely different from your own kendo and the ones of your kendo members back home.
This encounter of new kendoists is the best way to learn your strengths and weaknesses.
Some may make excuses why they did not do well at someone else’s dojo. But think about it for a while. We go out there and train at a different dojo because we want to challenge ourselves, not to show off, right?
So we do not have to make excuses. Just we should accept the fact that we did not do well and learn from it.
Those benefits are the reason why I always encourage my students to go out there and train with other people.
Now we all know the benefits of "de-geiko", so please go out there and train with many different people.
Hope this helps.