How long should a courtship relationship last?

less than 10 years os ok but more that is too match

Not counting reruns, but the "Courtship of Eddie's Father" lasted three years.

You'll know when it's time!

Courtship is not time bounded, the heart will recognize the feelings in the right time when two people are ready for such relationship.

No more than a year, IMO, and that's pretty generous.

If it's an actual courtship then you've already set the goal of an engagement or wedding at the end.

You're interviewing for a partner or wife, discovering long term relationship and goal compatibility, not discovering feelings and emotionally bonding in the hopes "love" grows.
Love grows between 2 people if they stick around each other long enough without external romantic interference.

Even if you work 100 hours a week and can only meet every other Sunday for an hour, a year offers enough time, IMO, if you're smart with the time you spend together.

So, no more than a year, preferably less.

Seems more important to be honest with your decisions, impressions, and what you're looking for than an actual time frame, though.

Must say I have no idea what you mean by "courtship relationship".
You mean when you can first have sex? You mean when you stop wooing her? You mean "When can I start taking her for granted"?

You should never stop courting, flirting and wooing. Both parties should keep doing that.
When you feel it is time to take it to the next level, by which I mean commitment, you will know.
I think having shared enough emotionally bonding moments is key. There should be some 'glue' between two people (substance) and depth to the relationship.

Some may get there in a month (not many I think though), others may take about a year. Depending on what you share (quality) and how often you see each other (quantity).
If things are still not going anywhere after 8 months - year, you may want to reconsider if it is going somewhere. And even in those 8 months there should be a serious buildup.

How much preparation a journey requires, depends on where you want to go, and who you are.

The courtship period for a life-long commitment, should probably be more than a few months, and should depend on how well you know yourself, and how well you can read other people. Longer for the inexperienced, shorter for those who are solidly self-knowledgeable and emotionally perceptive.

The courtship period for a one-night-stand, on the other hand, should probably be considerably shorter, and mostly consist of basic safety and transportation concerns, with perhaps a moment or two to consider how to get to work on time, and properly dressed, the next day.

A lifetime.
If you are lucky.

Lol escaping from realty with an understandable names :/