Just discouraging for a high school aged kid, and I must admit the parent too, to be made to feel guilty or lessor for not attending enough pre season open gyms.
Your DD should show up for one or two of the open gyms, and apologize profusely for not attending the others.
As Cannonball said, the amount of space available at most high schools is very limited.
When my DDs were in HS, open gyms were every day of the week. My DD is lucky to have them one day a week right now.