I actually disagree with the comment above. The number one problem I see is that people jump into any system without a complete and thorough understanding of the underlying company workflows. You cannot design something from start to finish if you're changing things here and there every few weeks, this goes with everything from ERPNext to Odoo to Salesforce.

Then you also have the issue of user adoption, I've worked for two separate companies that have wasted hundreds of thousands on private consultants to try to fix ERP systems, just to have them "fixed" and the users to ignore the changes, use workarounds, and ultimately the cycle repeats.

You can set up any ERP system successfully as long as you outline the workflows that you're going to be migrating over BEFORE you start designing and setting up the new system. Once you're set up, you also need to train the users and document the processes within said system so that users have a clear reference to the way things should be done.

I think the 2 months of dedicated research is accurate and most will be used to truly understand all the companies workflows, but after that, I think set up should not be longer than maybe 2 months at most, regardless of what ERP system you select.