However, Whangarei lawyer Kelly Ellis - who represented Herbert at her sentencing - said the women's cases were very different.
Herbert admitted the charges and was "very respectful and remorseful" while van Gaalen fought the charge and was found guilty at trial.
Herbert also risked going to jail but her guilty plea, remorse and efforts at rehabilitation meant the judge was able to reduce her sentence from the minimum starting point of two years' jail to a term of home detention.
An early guilty plea usually brings a 25 per cent sentence reduction.
The judge reduced van Gaalen's sentence by six months for her "extremely worthwhile contribution" to the community but she was not entitled to a further discount for admitting guilt.
Ms Ellis said two years' jail was not unreasonable or extravagant. The Court of Appeal had earlier ruled that the starting point for small-scale commercial dealing and cultivation was 2-4 years.
However, she had the "greatest sympathy" for van Gaalen.
"She was right on the threshold of getting home detention. Possibly if only a couple more grains of sand had gone into the other side of the scale, it might have tipped the balance."
Under New Zealand law, anyone caught with more than 28g of cannabis is assumed to be a dealer unless they can prove otherwise. Van Gaalen was unable to persuade the jury it was all for her own use or to give away to people aged over 18.
Van Gaalen is appealing her conviction and sentence. Her jailing has sparked a campaign for her release and reform of New Zealand's cannabis laws.
A judge can consider home detention if someone is sentenced to two years or less in prison.