1. 5G is necessary for professional deployments.
While 5G does provide superior performance when there is an excess capacity, the 4G is still better for the baseline performance as it has better coverage, propagation, and overall predictability

2. Size of antennas makes all the difference.
Size does matter, but only for rural, low signal strength applications. In busy environments such as convention centers, often the limiting factor is the noise and not a signal strength, which renders size of antennas irrelevant

3. The carrier X has superior coverage and can meet all your needs.

While regionally and locally there is often a carrier with better performance, at a country scale the picture is quite diverse and the only way to guarantee best performance is by leveraging all of the carriers simultaneously at all times

4. All SIMs are created equal

The two concepts you need to be aware of is network priority and data routing. The former is regulated by the carrier, the latter – by data brokers. It is not uncommon to see a SIM which routes your data from NY to NJ through a Singapore server, obviously adding to latency and degrading performance

5. Data is cheap, I can get unlimited plans for $30!

Unfortunately, these are consumer plans and have stipulations on limits and speed throttles after reaching a certain usage during the billing cycle. Business and enterprise data plans tend to cost notably more, but also provide higher quality, more reliable connection