thanks for you all's insight. Personally I do not like to or do leave room on any joinery. Just wanted to see the consequences if any that people might think of with said areas.
BB, my lay-out technique depends upon the wood and/or design. Sometimes Mill Rule, sometimes datum line square rule, sometimes edge rule square rule, sometimes french scribe, sometimes sauterelle lay-out (bevel), mechanical pencil, framing square, ruler from combination square, tape measure, 20/16 vision, always attempting dead on replication of design, spans and heights within 1/16th of an inch.
mo