It depends how you're buying your car.
If you're buying outright and anticipate a certain future value, true residuals count and may influence your buying decisions if you don't want to lose a fortune picking one car over another.
If you buy on PCP at a monthly rate you're happy with, then residuals aren't your problem, same with leasing. You hand the car back at the end, no matter what. That being said - perceived residuals influence your monthlies.
If a TCR is going to cost you £600 a month (inclusive of deposit down), in my mind, that's horrendous for a Golf - you could lease an S4/RS3 for that.
I've got a 2018 and a 2019 Polo GTI+, both bought outright and I put back into savings my perceived depreciation, based loosely on PCP GFVs and history of the previous model. I'm expecting that those "£23500" Polos bought for £20700 will be worth £13000 at 3 years old (GFV is £11500) to put away about £240 a month each to cover the depreciation and a bit of inflation for the next one.