humidor beads. do i still need hygrometer?

[victory01]

I started with 70 (and still have 3 humidors at 70) but just set my new 100 count up with 65 for my i s o ms.

If I was to start over I'd just stick with 65 ('cause you know you're gonna end up with a bunch of i s o ms sooner or later).

so i should keep cigars at 70 and isom cigs at 65?
is this a hard fast rule? or preference?
im just starting out and dont really have the cash to start up 2 humidors.

thanks