Roger,
For what seemed a very long time, I was buying tools and fettling them, fixing up things in my workshop and generally not completing many projects. Slowly the balance changed and then I found myself making one thing after another without (the need for) a new tool or any improvement in my workshop. I then realised that I was wasting time because I had learnt to live with various inefficiencies in my set-up and that life really would be better with a new plane, spokeshave or whatever.
These days I figure on completing two projects and then doing one workshop project or making one (big) tool purchase as a way of seeking some work/play balance.
Now, three quarters of the way through a second rocking chair I have decided on the next tool - actually I have ordered it.. (two projects so it's OK isn't it?)