Whether it's reasonable depends on the distribution, not just the duration.
A 2 hour onsite with the candidate being rapid-fire interviewed by six different different teams and a 20 minute call every couple weeks for three months are very different (and select for very different types of candidates) despite having the same overall duration.
A 2 hour onsite with the candidate being rapid-fire interviewed by six different different teams and a 20 minute call every couple weeks for three months are very different (and select for very different types of candidates) despite having the same overall duration.