I have few thoughts to share:

Your question is why my primary plan is to always "Bug In". Home is where my supplies are and where my plans are made for converting areas of my home to hold the other family members that either show up or that I am able to gather in.

I have faced the inevitable fact that some critical medical supplies may come up in short supply and that casualties will occur as more time passes without the infrastructure being restored.

I do have agreements with friends and relatives to shelter each other if I had to leave my home since habitability was no longer possible.

IMO, BoB's are primarily meant for cases such as a house fire, flooding, HazMat Incident upwind of my home, etc.

Just in case I had to relocate to the woods, I regularly go camping in those areas that have possibilities. I also usually take the back roads to get there, driving slow and looking the area over as I go.

There really isn't a perfect answer to your question as everybody's situation is different and every possible threat will be different in several ways from the planning that has been made.