It depends on your personal ability and context, and hopefully those two things align. If you are playing in an amateur/community orchestra, the music being created is typically held to a different standard than if you where playing in one of the best orchestras in the nation. While most music directors will select music that is within the reach of their orchestra, invariably that is not always the case. This could be because you are on the lower end of the spectrum of abilities within the orchestra, or it could be because that particular repertoire is significantly more challenging for your instrument than the others. Mozart at the tempos some orchestras decide to take comes to mind. His work is typically seen as relatively scalar and "simple" compared to other composers, but there are some extremely challenging bass parts as a result of passing lines from the violins to the basses and back again.
While it can be great for your bass playing and your understanding of music in general to learn all of these parts even if they are under tempo, sometimes you have to make realistic judgement calls. Accepting defeat too early when more diligent practice could make something within your reach is a bad habit to get into, but if your orchestra has decided to play Der Fliegende Holländer and it just isn't going to happen, a backup plan is usually a good idea.
In those situations I agree with in tune and in time, and leaving enough space for the players who are going to make it happen. That could mean the first note of the subdivisions, that could mean the first and third notes of 16th passages, that could mean a well timed cough that conveniently takes you out of the running for the bar in question. Most of the time those passages are few and far between so your contribution to the rest of the piece far outweighs that particular moment.
Professional orchestras are a bit of a different ball game. Many of the "impossible" passages are on the audition list as excerpts, and few professionals would admit to playing the storm less than admirably. If it is in the standard repertoire, then it is expected to be played. Some of the particularly challenging works don't come up very often, but they can also be extremely rewarding if you do conquer them. Modern works, world premieres, and really non-standard repertoire can be different. Some composers write things that just don't or shouldn't happen on the double bass. Depending on the amount of rehearsal time allocated to it and how long you have the part for it is expected that you bring your A game, but sometimes conductors/colleagues will look the other way.
Keep in mind that an extremely musical audience with an eye and ear for what the bass section is doing at all times with an intimate knowledge of the repertoire are the exception to the rule. Sometimes what they don't know doesn't hurt them.
Edited to say: I sat assistant to a fantastic principal bassist who pointed out the difference between our professional concertmaster and the amateur second desk. Game face. Learn to ditch the deer in headlights look, and especially the "well that was a disaster" look of defeat before and after challenging passages. To reiterate, what they don't know doesn't hurt them. Don't make it obvious when it doesn't need to be.
