The first thing to do is to create a camera profile on any mission planning software of your choice. Check out this post. This will allow for the correct overlap percentage on mission planning.
Now for flight heights. When doing a transmission corridor, between 200 ft and 225 ft is great. This will provide sufficient detail of the transmission structures and even capture guy lines. When you need finer detail (i.e. substation) then 150 ft is great.
For a corridor mission plan, I recommend to fly to the left of the structures and right of the structures, down and back. You can get a 300 ft ROW from a single pass but more often then not you will always fly back home. So just to the left and right gives you a great 300+ ft corridor at 200 ft AGL.
To connect multiple flights. This is easy, just get 20+ ft of overlap from your previous flight and this one and you are golden!
The only time you will need to possibly make any changes to the final processed data would be if you move the base station to a new location and the accuracy of your base station location has some error. In this case you would upload all the flights that used base station location number 1 to one project in the ROCK cloud then do the same for all the flights during the second base station location. Then put these two projects in a folder and use the compare function. At this point you can adjust one dataset to the other and correct any offset between the flights. ( it is usually very minimal )
Now we are adding the ability in the cloud to generate deliverables from a compare project, but for right now. You will take note of the offset x,y,z and go back to your original project and apply this and save. When you process or export these changes will be saved to your data.
BACK to the flight planning,
The M300 gets around 35-40 minutes with the R2A and we flew a 7 mile corridor with 1 set of batteries!