Site survey "soak time" for BR1/BR2 using VZW & ATT sims in semi-remote areas

Hey All:

I’ve got to do an LTE/5G survey for several locations at a customer’s sites. I’m taking a BR2 with 2x each of VZW & ATT SIMS and an 82G antenna.
What is the recommended time I sit/let the router soak at the remote sites in the survey vehicle before moving on?
I’ve only done 40 site surveys with this tech in total, and these sites coming up show marginal coverage for both ATT & VZW. TMO does not operate in these areas. All sites are CONUS, in the Pac, NW.

These were surveyed last year with a 15-minute sit/soak time per site and the performance was abysmal with a 20G Mobility and 40G Mobility antenna.

I’m hoping to make this next survey worthwhile. All my previous surveys have worked great just using my 40G mobility.