Yes, and I'll give you the honest case rather than the sales pitch. A good interior designer usually adds more value than they cost, through trade buying power, the mistakes you don't make, and a process that's quicker and far less stressful than doing it alone.
The biggest myth about hiring a designer is that we're not worth the money. I understand the worry. A fee on top of everything else feels like an extra. But it's the wrong way round: we are value added, and the value usually shows up in places people don't think to look.
Buying power you don't have on your own
Our purchasing power is far larger than a client doing a one-off refurbishment, and the response from suppliers speaks for itself. Trade pricing, priority, access to things you simply can't buy off the street. On a whole-home project, that difference alone can go a long way toward covering the fee, before you count anything else.
Less time, and far less stress
The whole process is quicker and less consuming when a designer runs it. You have the benefit of a cohesive team of professionals who respond, and who understand that timing matters. And you're supported the whole way through, with clear financial reporting and spreadsheets showing exactly where you are on the contract at any moment. You're never left wondering where the money has gone or what happens next.
A good designer will also stop you spending
Being worth the money sometimes means telling a client not to spend it. I once talked a client out of a substantial spend because they only intended to stay in the property briefly, had already paid too much for it, and were sitting on a likely loss. Pouring more money in wasn't in their interest, so I said so. A designer who only ever encourages you to spend isn't looking after you.
Why use a designer at all, if all you want is the ordinary?
If you're weighing it up, it's worth being clear on what the fee actually buys. I've written separately about what an interior designer costs in New Zealand, and how the different fee models work. Put the fee next to the trade savings, the avoided mistakes and the time you get back, and the sum usually looks very different from the way it first appears.