Too Much Humidity?

[Joseia]

I've been reading some orchid culture sheets and have a question about humidity. If a culture sheet says a certain cattleya species likes a relative humidity of 50-60%, but I am giving the same orchid 70-75% in my terrarium, is that a problem? My terrariums keep an average humidity of around 75%, temps range from 83 during the day down to 69 at night, and fans provide very good air movement - no mold or fungus spotted yet after 4 months. But if I have a plant in there that does not require so much humidity, will that slow it's growth? Accelerate growth, or have no effect? I am currently growing mostly cattleya alliance orchids, with some dendrobiums and a couple of vanda alliance plants as well.

I put these plants into terrariums because it is difficult to keep humidity above 35% in our home during the winter, even with humidifiers running. Are the orchids that need 50-60% RH better off in 35% RH on the shelf, or 75% in a terrarium?