Personally, I do not think it necessarily matters. I have published 8 hubs on the last 2 days of the month for the last 4-5 months. This is primarily due to deadlines, my primary occupation (education) and the care of my son (autism) and family.
If I could identify one disadvantage, it would be the HubPages community that follows me may not get a fair chance in seeing, reading or commenting on them. Although I highly value their input and support, the primary goal of successful online writing is for Google to index the Hub and have it effectively ranked for all readers on the web. Those factors are affected by a searchable title, sub-title, a clear and concise summary and comprehensive content - not timing. (in my opinion and experience)
Although, I guess it could depend on the audience and the purpose of the Hub. I used to write HubPages tutorials and community related Hubs. I would space out the publication of those types of hubs instead of lumping them together. This will give your readers and Topic followers a chance to see them as they pass through the feed.
Best wishes on your online writing success, MissOlive / Marisa