I use Clip Studio Paint (quite close to Photoshop) and I use a combination of straight and curved lines, depending on what needs to be done. Also, to make my ink seem a lot more organic, I use the textured pen, a tool that makes the ink "bleed" on the paper.

As for how I do it, simply, I just hold down the shift button while inking to get a straight line. However I only use it for basic room and building stuffs. Anything else like furniture or life effects I try my best to do it by hand. Mostly because in real life, we have a lot of straight lines going on at the base. But anything that could be considered as "handmade" or "organic" or even "old" has to be drawn by hand or it would come across as too stiff. There's a balance to how backgrounds can and should be made.