Question: Can I change the sequencing read lengths of the i5 and i7 indices?
Answer: The final configuration of a Visium Gene Expression Library is the following:
The i5 and i7 reads are necessary to identify the Sample Indexes. These Sample Indexes are needed to distinguish between pooled libraries and are used for demultiplexing. If this read is shortened, it will be difficult to demultiplex pooled samples. If only one sample is being sequenced in one lane, the impact of a shorter i7 read may be diminished.
It is best practice to adhere to the recommended sequencing lengths.