Allways wash tanks/reels or trays after processing, it is few minutes more of work, but preventing lots of troubles later.
Allways use wetting agent in separate cannister and film out of reels. Do not let wetting agent to come in contact with reels/developing tank. Wetting agent can built onto reels and this can make two probelms:
1. Contaminate developer
2. Make loading films in reels difficult because of built residues in reels.
Next, measure precisely how much chemistry you developing tank can accept. For example, I loaded reels with notimportant film, put them into tank and filled tank with water untill it was completelly full. Then I poured water from tank into measure jugs (calibrated ones, bought from chemistry lab equipment manufacturer). When establich amount of chemistry my tank can accept I allways use that amount when process.
For example your tank can accept 500 ml of chemistry when reel with 120 film are loaded into it, in order tank to be full. So, allways use 500 ml of chemistry when processing film, and no matter what manufacturer said what minimum of chemistry is enough. Make same measuring for example for 2 reels both with 35mm films, or whatever tank/reels combination you use. With this I never had developing problems because of not enough chemistry. I had problems because I wrongly loaded two 120 films on one Jobo reel (using red separator), but I learned how to load films properly, and no problems since then...
Or, (if you reuse chemistry, not one shot) simply, when you pour your chemistry into tank pour enough chemistry from bottle to tank to be full. This way you will allways have for sure enough chemistry in tank...