Even though Mike & Angelo was only Mike & Angelo in name considering they had I think it was a three year gap where they didn't actually have a Mike (and the last but one series as well) whereas there was always an Angelo
I don't recall that long a gap without a Mike. MIchael Benz was in most series after he joined, even after hitting puberty where the character was adapted into an awkward teenager (towering over Angelo by that stage).
A friend of mine, Steven Geller played the new Mike in the final series. Unfortunately he passed away in 2015 of a brain tumour, aged just 30.
Michael Benz first appeared in 1993 and stayed with the production until 1998. Steven Geller as stated appeared in the final series in 2000 and the original Mike was in it 1989-1991. Having misremembered I've checked it out and there were two series with no Mike - Series 4 in 1992 and Series 11 in 1999.
It was still all guns blazing as late as series 12 though and it was a popular show for CITV, having survived four presentation incarnations (and a franchise change) as it was. The 1990s were a period of really long running series particularly on CITV, most of which would just reach into the next decade.
Basil Brush Show CBBC 2002 onwards is your traditional sitcom format, it effectively predated Mrs Browns Boys with the breaking of the fourth wall on many occasions, shots of the set, the crew and on occasion self referencing itself as an cheap half-arsed production. It was actually quite a good little show I thought, and then Series 5 came along... ah well.
CBBC had a bash at Microsoap for a children's sitcom which lasted four series in the late 1990s and after the success of Tracey Beaker the various Dani Harmer fronted sitcoms came along - Dani's House being the first one, followed by its spin off, the imaginatively named Dani's Castle (which later lost its Dani character).