Is it possible to create a campaign without being tied to a date?

What I mean by this question is about the possibility of creation of campaigns-date independent.

For example: creating a campaign "One week" that I can use with many ads in different weeks of the year.

Steps:
1. I create One week campaign, seven days, no starting date
2. I create an ad the first day of the year, assign to the "One week" campaign and it is active from the 1st to the 7th of january.
3. I create another ad on day January the 15th and assign it to the same "One week" campaign, so it runs as well for one week, from the 15th to the 22nd.

The problem here is that, in my site, whenever I want to create an ad, I have to create a campaign tied to the ad, and there is no way I can reuse the campaigns, which turns the campaigns useless for the "days-driven" campaigns.

Are, then, campaigns just intended to solve the impressions and clicks cases?
Probably this is intended behaviour, but I would like to know if I am doing something bad or I can configure this easily.

thanks in advance