In continuation to the title, should we memorise all the number of various geometric isomers ? If not can you list which ones to memorise?
There isn’t a need to memorise it , you can dry different structures and check the number of g.i or optiocal isomers , but while drawing you might miss some of those during exam and hence it is said that you should remember those so as to give accurate and quick answer during exam
So is it good to memorise some isomers and while for others it would be better to give answers by drawing structure ?
Yes , although you can try and draw for each once at home and check of your answer matches with the answer or not.