Should theorems, proposition, conjectures, etc. share a common counter?
For example, is the following good, for a theorem and a proposition to share the same number?
Theorem 1. ...
Proposition 1. ...
What about sharing numbering for conjectures?
To quote from a review in Mathematical Reviews:
One practical criticism applies to this book as well as a large part of contemporary mathematical production: the various statements are called by different names, such as Lemma, Theorem, Proposition, Corollary; the first three are numbered independently of each other, while the numbers assigned to corollaries are functions of several variables; in addition, numbered formulae have their own separate numeration. The strain placed on the reader by this partial ordering is obvious, but apparently readers seek vengeance on other readers when they turn into authors.
Source: I. Barsotti, MR 23#A2419