It depends on the sensei/dojo. I was in one that required permission, and while the rule existed, it was expected no one would actually
ask permission to train in other Aikido dojos (one of the things that led to my being shown the door there
). The others I've joined encourage their students to move around and explore---altough that is one thing I look for when choosing a place. This is not that those who are more restrictive are wrong or inferior, they are not, but it is just not my way of being.
Just ask the sensei or a senior student what the dojo rules are.
Also, some dojos are not excited about hosting unexpected visitors (often the same ones that don't like their students wandering around from dojo to dojo). I find it best to call or write ahead to seek permission to train.
If the dojo is somewhat restrictive in visiting other places, your best bet is with another dojo in the same organization; if the sensei encourages exploration it usually doesn't matter.
When you are first starting out, visiting other places might be confusing, as there are often slight (or major
) variations in attacks and techniques and names, from style to style, or even dojo to dojo. If you are the type that needs to do it 'the right way' then don't travel until you are very comfortable in your home dojo. It is rude to visit another place and NOT do what the teacher is showing you, to the best of your ability, so go with an open mind and PAY ATTENTION to what is shown. Also, don't come back from a visit and tell your home dojo that THEY are 'doing it wrong'. The 'right' way is what is shown by the instructor, but a lot of times beginners are so hung up on getting it right, that they cannot accept many right ways and conflict builds.