Quoted from Kneissl:I put 1-2 years cuz i've slowed down the last few years.. but i've got 40 some in my history.. I guess I turnover a fair bit faster on avg.
Had around 70 total since the 80s, have always kept about seven scattered about the house (the number I can keep without being overcrowded in this little hovel) including today but haven't gotten a new one in several years because most of the seven I have now are keepers I've held onto for 20 or more years which I can't imagine selling, they're just too much good fun. But overall, maybe kept them average of 1 or 2 years.