In an area where you hardly get network for browsing, i think it's not advisable leaving your sim1 and two on because this will cause a hook in your connection. Maybe you have noticed it before, a situation where you are browsing, your connection will just suddenly stop working ,you will have to switch off your data and on it again. or you will have to put your phone in flight modethen on it again before you could regain your network

This tutorial not only help you in such occasions of regaining your data connection when force is loosed, I also switch off my sim one when am browsing and someone is pestering me with phone calls cutting my connection short in will have to off the sim while i keep browsing with my other sim. This is the major reason i have different sim for making calls and browsing.

You don't need to put your android phone in flight mood because someone is disturbing with calls. if your do the not sim one and two will loose network and you won't be able to run some systems on your mobile because they required your phone must not be in flight mood before operating such systems.

Without time waste let me quickly teach you how you can switch of your sim one or two in your android phone without putting your phone in flight mood.

How To switch of your sim on android without flight mood
From your android menu select settings

The next page click on sim management

now you can on or off any of the sim you think you don't need at a time

Like i said if you are in area of poor network always off one sim while you are using the other it will help get more stronger connection to when both sim is on. So when you are browsing and your connection stops just switch off both sim then switch on only the one you want to be using for browsing allow network to come after that start browsing .