Should I double up cake circles when making a wedding cake to make it more sturdy? Is it better to stack and transport or assemble on site?

I always double or triple stack my circles (on the bottom layer only) or use a sturdy board for support. Even if I stack at home or transport and stack onsite.

Foam core. Wrapped in press and seal. Various degrees of thickness. No shifting circles, no soggy circles. Transporting stacked vs. not stacked=depends on how many tiers, how sturdy your support structure is, what you used, what the road is like on the way there...so many things to consider.