this is a very difficult question as there are so many things which come into play
**how good your shadow memory is (how much you remember when you return) (eg: you can have a trip that lasts 1 hour but then return and only remember the last 10 minutes of it, which I assume often happens). When I did sets of 5 trips in a row without a break, the trips were quite long but then I only remembered snippets from the 1-3 trips, and lots of detail from 4 and 5th trip for example. So you end up doing a lot in a trip but then don't remember a lot of it thinking that it was a short trip. Its like this with normal dreams as well (meditate as soon as you wake up and suddenly you will notice all kinds of 'memories' popping up from dreams you didn't even know you had last night, its quite a wierd process, you suddenly remember a new dream, new scene, new conversation etc).
**which environment you end up with (environment which resembles physical is quite easy to judge time simply by how much things happen to you or how much you say (especially if you speak 'physically' there in words and sentences); environment which is nothing like physical (completely dark environments, etc) then can't judge time at all especially if you download knowledge telephatically in chunks)
**how good your shadow memory is (how much you remember when you return) (eg: you can have a trip that lasts 1 hour but then return and only remember the last 10 minutes of it, which I assume often happens). When I did sets of 5 trips in a row without a break, the trips were quite long but then I only remembered snippets from the 1-3 trips, and lots of detail from 4 and 5th trip for example. So you end up doing a lot in a trip but then don't remember a lot of it thinking that it was a short trip. Its like this with normal dreams as well (meditate as soon as you wake up and suddenly you will notice all kinds of 'memories' popping up from dreams you didn't even know you had last night, its quite a wierd process, you suddenly remember a new dream, new scene, new conversation etc).
**which environment you end up with (environment which resembles physical is quite easy to judge time simply by how much things happen to you or how much you say (especially if you speak 'physically' there in words and sentences); environment which is nothing like physical (completely dark environments, etc) then can't judge time at all especially if you download knowledge telephatically in chunks)