I think that is a question of the looping techniques you have at your
disposal, and the extent to which the tools you use support an
improvisational approach. And the extent to which you have become familiar
enough with those techniques to comfortably work with them live. looping
definitely doesn't have to be locked with the same thing repeating forever!
To me that is really the entry level of looping, and moving past that to
solve the problem you mention is where it really gets interesting.
** first, i am probably not the most evolved looper guy on this list, i tend to use it as only about 10-50% of any given improv situation . . . so i basically agree that looping technique is going to have a lot to do with the situation. that being said, i think that the looping issue also has to do with the context within which you improvise. some are going to be more conducive to looping than others. i feel that the machine is not always so quick as the people who are playing - - they can jump into other waters very, very quickly if you're doing free improv. sometimes it's better for me to ignore the looper for a while and bring it in later. so, for me, larger groups are often less conducive and duos and trios can be more so - - and it also depends on whether or not there are other people looping . . . sets up the context (or not).
stig