It’s difficult to say if I would have changed things up while I was still progressing, as I was already maxed-out at Rank 435 when this came in.
In general, I only use the gem-to-reselect option if:
1. the node is blocked because the TF is on a mission, or
2. it’s a TF I really hate using on that node – for example desert nodes are notoriously difficult with Heatwave or Sentinel due to all the missiles, flying pigs, falling monoliths, and walking mortar towers. It’s either a death-trap or your scoring will be severely impeded.
But even then, it’s pretty rare that I’ll use a gem to change my TF. Usually only if I’m super bored and I want to run that node right away, but otherwise I can’t see myself wasting a lot of gems on that since they’re so difficult to come by.
Also, it’s a matter of profit. Certain nodes pay out better (on average). So I wouldn’t necessarily swap my TF in a Pig City node, but I’d consider it on a beach node.
The other thing to consider is that your swap is no guarantee to get you a TF you want, so then you have to make another decision whether or not to use another gem. And so on.