If raid a gym will gave u 10K XP for a level 5 boss which is equivalent to mass evolution of 20 pokemons to get the same amount XP.
Time taken to raid a gym is about 120 seconds + 300 seconds + maybe around another 100 seconds to catch the boss which add up to 520 seconds which is equivalent to about 9 mins to complete 1 raid battle. I am calculating to the extreme.
So if you can mass evolve more than 20 pokemons for 9 mins, it still worthwhile to do a mass evolution if you wanted to level up fast.
Got time then dun waste
I agree
But if the intention is to 30 mins just to mass evovle,
I am saying its too much effort
Many nowadays either
1. Assuming free raid pass ROLLED over,
See 2 lvl 5 side by side and around same timming hatch, they will lucky egg it and raid to clear raid pass
Then whatever time left, yes just evovle whatever pokemon to max out time
2. Like the 3 xcatch bonus event or hatching some might plan in such a way egg hatch plus community day ( neeed to catch pkm anyway, so on lucky egg)
Theres no right or wrong on do it
Thou mass wvovle is the fastest to get the max exp from.it
So it boils down for effort to do it
Personally,i wont mass.evovle for full 30 mins, too tirrinf and boring