Why is upgrading from an LTS to LTS more safe than doing upgrades from the Short Term Supports?
Any upgrade is a risk. Things can break in between. Power failure can be an issue. So purely based logics going from LTS to LTS is less risky than going LTS->NON-LTS->NON-LTS->NON-LTS->LTS.
The whole idea of using an LTS is to not upgrade in between LTSs. You get a lot of stability in exchange for not getting the latest software out-of-the-box.
And yes; if possible I would always go for a reinstall. A reinstall has a side-effect: it will remove all packages you installed and that you never used.